KEY POINTS FROM THIS ARTICLE
— As part of capturing the Senate this year, Republicans knocked out the final remaining Democratic senators from a group of 20 states that have consistently voted Republican for president since at least the 2000 election.
— A quarter-century ago, Democrats held nearly a third of the Senate seats from these 20 states. But that tally was down to just 2 leading into this election, and Republican victories in Montana and West Virginia reduced it to 0.
— Additionally, 5 other states backed a Democratic presidential candidate at least once this century but voted for Donald Trump in all 3 of his elections. Republicans now hold all of the Senate seats in these states as well.
— In total, these 25 states hold half the Senate seats. Realistically, Democrats can’t win future Senate majorities without making at least some inroads back into this now fully Republican bloc of states.
Senate Democrats shut out of the reddest states
As part of winning back the Senate majority in 2024, Republicans completed a task that had been years if not decades in the making: They finally won all of the Senate seats in the states that have consistently voted Republican for president for at least the past quarter century.
There are 20 states—which account for 40 Senate seats in total—that have voted Republican for president in at least every presidential election this century, and Donald Trump won all of them by double-digit margins in 2024. Those 20 states are shown on Map 1.
Map 1: States that voted Republican for president 2000-2024
For the first time in the history of Senate popular elections, Republicans will hold all 40 of the Senate seats from these states after flipping Montana and West Virginia.
Five other states—Florida, Indiana, Iowa, North Carolina, and Ohio—have more often than not voted Republican for president this century, including backing Trump in all 3 of his elections. Republicans also will hold all of the Senate seats in these states, following Sen. Sherrod Brown’s (D-OH) loss in November. That in addition to the 20 states identified on Map 1 equals 25 states, or half of the entire membership of the Senate (50 seats). These account for 50 of the 53 seats Republicans will hold starting in January. The 3 additional Republican Senate seats are from Maine, which has voted Democratic in all 7 of the presidential elections this century, as well as Pennsylvania and Wisconsin, which are presidential battlegrounds that voted for Trump in 2016 and 2024 but not 2020.
Map 2 shows the makeup of the Senate following the 2024 election.
Map 2: Partisan makeup of Senate following 2024 election
Democrats now hold 10 seats in states Trump won in 2024: both seats in Arizona, Georgia, Michigan, and Nevada and a seat apiece in Pennsylvania and Wisconsin. Granted, we just saw the best Republican presidential performance in 20 years, but this does help illustrate the Democratic challenge in the Senate: They have been doing better in the most competitive presidential states than the Republicans, but they still will find themselves in the minority next year. Sen. Susan Collins of Maine is the only Republican in a state that Kamala Harris won in 2024—Collins’s seat is up in 2026, and she has already said she is running again.
Collins is now the lone outlier among all 100 senators as someone who continues to hold a Senate seat in a state that hasn’t supported her party’s presidential nominee in decades. Such outliers were important parts of past recent Democratic Senate majorities, but they will now be all gone. Let’s briefly go through the history.
Map 3 shows the partisan makeup of the Senate immediately following the 2000 election—our starting point for identifying the 20 reliably Republican presidential states shown in Map 1.
Map 3: Partisan makeup of Senate following 2000 election
Notice how much different the post-2000 map looks compared to the post-2024 map. First of all, there are way more split delegations on this map than on the post-2024 map. Following 2024, there will be just 3 split Senate delegations: Maine, Pennsylvania, and Wisconsin (this counts independents Angus King of Maine and Bernie Sanders of Vermont as Democrats, the party with whom they caucus). Back in 2000, there were 12 split Senate delegations, nearly a quarter of all the states. That did effectively decline to 11 by mid-2001 however, as Sen. Jim Jeffords of Vermont—Sanders’s predecessor in the Senate—switched from Republican to independent and jumped to the Democratic caucus, giving the Democrats a 51-49 Senate majority for roughly a year and a half before Republicans won back the majority in the 2002 election.
More to the point, you can see the Democratic presence in the red states identified in Map 1. At the start of the century, Democrats held 5 of 6 seats in the Dakotas/Montana. They had a more robust presence in the South, including holding both of Louisiana’s seats and, following the 2002 election, both seats in Arkansas, as Mark Pryor (D) beat an incumbent Republican that year. We point this out just to note that while the history in these states is of Republican gain and Democratic loss over a quarter century, Democrats did still sometimes actually flip control of Senate seats in these states since 2000, but they eventually lost them in a future election. For instance, Pryor would lose to now-Sen. Tom Cotton (R) in 2014, an election year that hastened the decline of these red state Democrats, as we’ll discuss below. The last Democratic flip in one of these states came in the 2017 Alabama Senate special election won by Doug Jones (D), but he would lose that seat in a 2020 regular election.
Back in 2000, Senate Republicans also had more of a presence in states that are more Democratic at the presidential level, as they still held seats in states that consistently voted Democratic for president this century, like Illinois, Oregon, and Rhode Island, and they even held both seats in a few states that would go on to vote against Trump all 3 times: Colorado, New Hampshire, and Virginia. Republicans also held both seats in Maine, although they do still hold one there. But Republicans are shut out from the 18 other states that never voted for Trump.
Table 1 tracks the biennial partisan makeup of the 20 red state Senate delegations starting in 2000, noting their status immediately following each even-numbered year election.
Table 1: Number of Democratic senators in states that only voted Republican for president since 2000
Democrats had a little less than a third of these states’ Senate seats (13 of 40) in 2000, and they consistently held at least 10 seats from these states until the 2014 election. This midterm Republican wave election held during Obama’s second term saw Republicans net 9 Senate seats, including 6 from this group of states (Alaska, Arkansas, Louisiana, Montana, South Dakota, and West Virginia). That knocked the number of Democratic seats from these 20 states down to just 4, with the total finally falling to 0 in this year’s election.
Twelve years after that important 2014 election, that same class of Senate seats (Class 2) will be on the ballot for another midterm, 2026, this time taking place during the presidency of a Republican, Trump. At first blush, Republicans seem overextended: They are defending 22 seats, while Democrats are defending just 13. However, much of their defense should be easy. Map 4 shows the Senate seats up in 2026, which assumes special elections in Florida and Ohio to fill the seats of the likely next secretary of state, Marco Rubio, and Vice President-elect JD Vance. Only one of the currently Republican seats up in 2026—again, Collins in Maine—is in a state that did not vote for Trump all 3 times he was on the ballot. And of those 3-time Trump states, only 1 of the 21—North Carolina—didn’t vote for Trump by double digits in 2024.
Map 4: 2026 Senate elections
Democratic Senate majorities, including the one that ended with this most recent election, have often relied on at least a few members from states that were unfavorable to the party at the presidential level. A future Democratic majority probably does too—winning all of the seats in states that voted against Trump at least once would only get Democrats to 50 on the nose, technically enough for a majority with a vice presidential tiebreaker but only achievable, at the earliest, by 2030, thanks to Sen.-elect Dave McCormick’s (R) narrow victory in Pennsylvania this year. And that would require the Democrats to win or hold all of the seats from these 25 states over the next 3 Senate election cycles, hardly a given.
So the challenge for Democrats is figuring out a way to once again win in states that have usually or always voted against them at the presidential level this century. The recent historical trend in such places is, for Democrats, daunting to say the least.