Elections for the U.S. Senate are held every two years. Senate seats are divided into three classes, mostly to ensure that roughly one-third of the Senate is up for re-election every two years, special elections notwithstanding. Senators also serve six-year terms, meaning a state will take an election year off from Senate races after two of its seats have been filled.
The three Senate classes are also relegated to their maps based on how the terms are staggered. There’s three maps that rotate every three election cycles as terms expire.
Since Senate elections are held every two years, it means they will run concurrently with a presidential or midterm election year. However, since terms and seats are staggered, a map that was previously held during a midterm year will be held during a presidential year once the six-year terms expire.
That’s exactly the place this year’s Senate map finds itself in this year. In 2018, thirty-three Class I Senate seats were contested during the midterm elections, with two special elections. This year, those same thirty-three seats will be up, plus two special elections in California and Nebraska, coinciding with the presidential race.
At a glance, twenty-six Senators, fifteen Democrats, two Independents, and nine Republicans, are seeking re-election, while two Republicans, three Democrats, and two Independents, are not seeking re-election.
This map proved brutal for Democrats in 2018, as Republicans actually slightly expanded their majority that year by flipping four seats, for a net gain of two, despite it being a good Democratic year that saw the party gain control of the U.S. House and flip seven governorships. The Senate map was not only difficult for Democrats in terms of resources, as Democrats had to defend twenty-three seats, while Republicans only had to defend nine. Democrats were also playing defense in ten states won by Donald Trump (R-NY) in the 2016 election, while Republicans only had to defend an incumbent in just one state won by Hillary Clinton (D-NY): Nevada.
A changing political landscape among working-class communities in Indiana, Missouri, and North Dakota allowed Republicans relatively easy flips, while Florida’s realignment started to begin, when Republicans ousted Bill Nelson (D) in a semi-upset.
Democrats ousted Dean Heller (R) in Nevada and won the open seat in Arizona.
Had the year been more auspicious for Republicans, they likely could have contested much more territory. And despite 2018 being a good Democratic year, their prospects fell short in Tennessee, Texas, and the special election in Mississippi.
The same map is presented to the parties and the public this year. Democrats have virtually no hope of regaining three red-state seats they lost in 2018 and face the similar problem of lopsided defense. Republicans, on the other hand, aren’t in immediate danger of losing any seats at the moment, and can benefit from an election year in which the generic ballot might be Republican-leaning. If Trump regains momentum after the Biden-Harris switch, Republicans might even play more offensively, as Democrats have open seats in competitive states and must face some decent Republican recruits where unexpected.
Democrats were also dealt a massive blow with the retirement of Joe Manchin (I-WV), virtually guaranteeing Republicans flip this deep-red seat and erasing Democrats’ margin for error in other states. Essentially, they have to run the table to hold all seats while also holding the presidency to retain the majority.
Since Senate elections are becoming increasingly more in line with presidential results in a given state, Senate outcomes are almost certain to correspond to presidential results. Only five states have split Senate delegations, one that includes a member of both parties: Maine, Montana, Ohio, West Virginia, and Wisconsin. This is the lowest number of split delegations since the direct election of Senators began in 1913.
This week, we’ll examine our preliminary forecast and discuss the most competitive races that are likely to determine the balance of power in the upper chamber.
Safe: These seats are highly unlikely to be contested and the incumbent party has heavy odds to win these seats.
Likely: One party has several distinct advantages, but the race has potential to become engaged or see a thinner-than-usual margin.
Leans: One party has a certain set of advantages, but the race is by no means a cake walk for them.
Tilts: One party has a slight advantage that cannot be overlooked in the analysis of the horse race. These seats are certain to remain competitive.
Toss Up: No party has a distinct advantage. These races will also likely rely on top-of-the-ticket energy.
The Toss-Ups
These are the seats most likely to be decided by the closest margins and to determine who will control the Senate for the next two years.
Michigan – Elissa Slotkin V. Mike Rogers
Four-term incumbent Debbie Stabenow (D) defeated Michigan’s last Republican Senator, Spencer Abraham, in 2000. She won two resounding re-elections, but narrowly took a fourth term in 2018, despite the year being good for her party.
Now, the race is wide open with her retirement. Trump’s polling energy against Biden in Michigan seemed good enough to help Republicans flip this seat for the first time in over twenty years. Now that Vice President Kamala Harris (D-CA) is the presumptive nominee, the political calculus of this race changes significantly.
Ex-CIA member and three-term Congresswoman Elissa Slotkin (D, MI-07) secured the Democratic nomination last week. She won three close elections in her Lansing-based district and brings fundraising and campaign enthusiasm to the race.
She faces former Congressman and FBI professional Mike Rogers (R). Rogers was mulling a presidential run last year, but instead pursued a Senate run. Rogers has earned the endorsements of Trump and other notable officials. Rogers has $2.5 million cash-on-hand to Slotkin’s $8.6 million war chest.
The 2016 and 2020 elections have given Michigan a slight Republican lean relative to the nation overall, a sign of some fundamental changes among the state’s heavily-unionized, working-class voting base. Diverse urban and suburban areas are likely to go to Slotkin, but the battlegrounds will be found in areas like Grand Rapids, Flint, and Saginaw, communities that were crucial to Trump’s upset win in 2016.
The Michigan GOP suffered from intraparty fighting and clerical issues that cost them winnable races in the 2022 midterms. If the party hasn’t organized their business by Election Day, we might move this rating in Slotkin’s favor.
This one will certainly come down to presidential results. Since Michigan tends to vote bluer down ballot, Rogers might have to outperform Trump by a couple of points to win this race. If Trump doesn’t win Michigan, Rogers is probably already underwater. Either way, the next Senator from Michigan will have a federal investigative background.
Nevada – Jacky Rosen V. Sam Brown
Jacky Rosen (D) was the only Democrat to oust an incumbent Republican, Dean Heller, in the 2018 midterms. Nevada is perhaps the only notable state that regularly overestimates Republican support in polling. Heller seemed to be in the driver’s seat in 2018, only to lose to Rosen by five points.
Rosen hasn’t exactly been a vocal presence in the Senate, but Nevada voters, so far, seem keen on returning her to Washington. She has held narrow leads in the polls against Army Veteran Sam Brown, who sustained severe burns due to an improvised explosive device injury while serving in Afghanistan in 2008.
Republicans almost ousted Catherine Cortez Masto (D) in 2022, with Adam Laxalt (R) coming up short by just a few thousand votes. While this year’s race might not be as close, it will certainly be within a few points.
Nevada’s political profile is entirely unique from those of other states: low-college-educated, highly transitory, and ethnically diverse, it makes sense why Nevada has been a blue-leaning swing state since the late-2000s.
However, Republicans might be able to capitalize on the tectonic shifts of the Latino demographic leaving the Democratic Party, a valuable voting bloc in the Silver State. Rosen leveraged her representation of the suburban-Las Vegas NV-03 in the U.S. House before her Senate run. If she still has that kind of support in Nevada’s largest city, it puts her in a decent starting position.
Rosen has just over $10 million in war chest, while Brown sits at $2.5 million cash-on-hand. However, Brown just cleared a large primary and has already raised $7 million total.
Nevada’s presidential outcome might have more of an effect on this race than the same dynamic would in Michigan, as Trump has held massive leads in the polls here all year and continues to hold the line even with Harris on the ballot.
However, if the GOP is currently being overestimated in polling, then Brown is already underwater, as he trails Rosen by a larger margin than Harris trails Trump. The picture might not be rosier for Trump, who might not have much of a margin for error if the polling is overestimating his stance in the race.
Ohio – Sherrod Brown V. Bernie Moreno
Ohio was once one of the nation’s most crucial swing states. However, the Trump Era has shifted the state markedly to the right, as the working-class population that once gave Democrats massive margins of victory have jumped ship in search of redder pastures.
Three-term Senator Sherrod Brown (D) faces Colombian-American businessman Bernie Moreno. Moreno was seen as one of the less electable Republicans running in the primary, but has not trailed too far behind Brown in polling thus far.
On paper, Brown should have this race locked up. As a moderate Democrat with a long record in Ohio politics, Brown faces the biggest challenge of his political career this year. His state has moved much farther away from him in recent years that he might already be a slight underdog. Had another Republican won the primary, we might already insist he’s not favored to win.
In 2018, Brown faced an underwhelming opponent in a good Democratic year. Polling indicated a low-to-mid double-digit win for Brown, but he only won by around seven points. These were the first alarm bells for Ohio Democrats, with the second set coming in 2020, as Trump, initially expected to only narrowly win Ohio, repeated his unprecedented eight-point margin of victory that year.
While Republicans suffered in some congressional districts in 2022, the political moods don’t seem to be shifting. Indeed, Trump has maintained his levels of support and we wouldn’t be surprised if he took the Buckeye State between ten and fifteen points.
That said, Brown would need a corresponding level of crossover support, something largely unlikely in a polarized electorate in a state racing to the right.
Tilting R or Tilting D
Montana – Jon Tester V. Tim Sheehy
Montana continues to be the political anomaly it always has been. A Rocky Mountain state surrounded by some of the most Republican in the country, Montana is the only one with a statewide elected Democrat, no right-to-work laws, and more liberal stances on certain issues.
Senator Jon Tester (D) was elected in the blue wave year of 2006, giving Montana two Democratic Senators. He won another squeaker in 2012 and rode the environment, despite slightly underperforming it, to win a third term in 2018.
Tester, although popular among constituents, might not be so lucky this time. Since 1972, Montana has swung against every incumbent president. Trump took Montana by sixteen points in 2020, meaning Tester already has a colossal amount of crossover appeal to rack up, with a few points more likely coming as the state is likely to swing against Harris.
Tester has also been trailing in the polls against former Navy SEAL Officer Tim Sheehy (R). Tester starts with almost $11 million in campaign cash, to Sheehy’s $3.2 million. Those numbers are likely to explode in perhaps a defining race of the season.
Arizona – Ruben Gallego V. Kari Lake
Arizona’s reputation as a Republican-leaning battleground has transitioned to a blue-leaning swing state in an incredibly short amount of time. Kyrsten Sinema (I) flipped this seat as a Democrat in 2018, but adopted more moderate votes on Senate policy, much to her caucus’ chagrin. She became an Independent last winter and is not running for a second term this year.
The race pits Congressman Ruben Gallego (D, AZ-03) against former news anchor and 2022 gubernatorial candidate Kari Lake (R). Gallego would be an ardently more progressive voice in the Senate than Sinema was, while Lake has ostracized some in the state GOP for her claims of election fraud in the razor-thin 2022 governor’s race.
This would be a pure toss-up if Sinema remained on the ballot as an Independent. We believe a fractious state GOP gives Gallego a slight advantage, although Trump has remained the favorite in Arizona polling, even with Harris on the ticket.
Safe R
West Virginia – Jim Justice V. Glenn Elliot
West Virginia was once the bread and butter of the Democratic Party via the blue-collar workers that makeup the state. Since the 2000s, the party’s support has collapsed almost entirely. Beloved moderate Senator Joe Manchin narrowly won re-election over a relatively weak opponent in 2018. Due to the evenly-divided Senate for two years, Manchin was a thorn in the progressives’ side. Manchin decided to retire rather than face near-certain political defeat.
Trump carried West Virginia by forty points in 2016 and 2020. The level of crossover support Manchin would have needed is virtually impossible to obtain the modern hyper-partisan era. Wheeling Mayor Glenn Elliot, or any generic Democrat for that matter, is unlikely to fare much better against charismatic Governor Jim Justice.
The political headwinds in the Mountain State make Democrats’ Senate math even more difficult than it already was. A safe Republican flip here, assuming the GOP holds their other seats, brings them to fifty seats in the chamber, with the vice president acting as a tie-breaker when necessary. If Republicans flip just one more seat, which we believe is on the table with the Montana race, Republicans win control regardless of presidential outcome.
Outlook
Republicans are currently favored to flip the Senate. We put them at reaching fifty-one seats, by flipping in West Virginia and Montana. Flips in Ohio and Nevada are also possible, but the races are much more competitive than the other two.
Democrats have outside chances of flipping seats in Florida, Texas, and Missouri, although these remain at farther ends of the competitive table than Democrats would probably prefer. With Trump almost certain to win Missouri and likely to carry Texas and Florida, Democrats would not only need to outperform the top of the ticket, but fundamentals as well. Missouri is no longer the swing state it was. Florida appears to have realigned significantly, although can still host competitive races. And while Democrats have chipped away the Republican guard in Texas, additional election cycles will be required to fully put the state in play.
Republicans have other pickup opportunities in New Mexico, Virginia, and possibly Maryland, but remain just as unlikely as Democrats’ chances in the aforementioned states.
In another column, we’ll analyze the states where both parties’ prospects are better, but still leave room for competition.
