Although most competitive Senate races in 2020 involve Republicans defending their seats, it’s a Democratic senator who tops the list of the most vulnerable incumbents in the chamber one year out from Election Day.

Alabama’s Doug Jones is running for a full Senate term after winning a special election in 2017, and he faces the difficult task of overcoming the partisan dynamics of a deeply Republican state. Michigan Sen. Gary Peters is the other Democrat running in a state that President Donald Trump won in 2016, but he is further down the list, since Trump won the Wolverine State by a much smaller margin.

[See October 2020 updates to lists of most vulnerable House members and senators]

Democrats are largely on offense in Senate races in 2020. They need a net gain of four seats to win the majority, or three if they win the White House since the vice president would be the tie-breaking vote. Most of the other senators in vulnerable positions are Republicans, two of whom are running in states that Hillary Clinton won in 2016 — Cory Gardner of Colorado and Susan Collins of Maine. Gardner is the second-most vulnerable in the country, given that Clinton won his state by 5 points and Democrats were successful there in 2018.

Considering the high-profile backlash to Collins after her vote for Supreme Court Justice Brett M. Kavanaugh last year, it may be surprising that she is further down the list, but that’s in part because of her strong personal brand in the Pine Tree State.

Campaign strategists in both parties suggested Republicans Thom Tillis of North Carolina and Martha McSally of Arizona were in more vulnerable positions than Collins. Tillis is facing a self-funding primary opponent. McSally, a former two-term House member, lost her first Senate race in 2018 and is only an incumbent because she was appointed to a vacancy, and she has a well-funded Democratic opponent.

Georgia Sen. David Perdue is near the bottom of the list. Democrats could have another potential pickup opportunity in an open-seat race in Georgia, but this list focuses just on incumbents.

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The presidential race remains an X-factor in all of these Senate contests, with its impact unknown until Democrats choose a nominee. In 2016, the presidential results in each state matched the Senate race results, so operatives in both parties are closely watching the presidential contest for signs of how it could affect these Senate contests.

The 2016 presidential results in these states were factored into the rankings, along with conversations with strategists on both sides of the aisle and race ratings from Inside Elections with Nathan L. Gonzales. On this list, senators’ names are followed by Trump’s winning or losing margin in 2016, the senator’s margin of victory (or defeat, in McSally’s case) in his or her most recent election and the race rating by Inside Elections.

Jones won a special election in December 2017 after a majority of Alabama voters apparently could not stomach voting for former state Supreme Court Chief Justice Roy Moore, who faced allegations of sexual misconduct involving young women. Next year, Jones faces an uphill battle running for a full term and will need voters who back Trump to jump to his side as they move down the ballot. Moore is running again, and his baggage could boost Jones’ chances if he’s nominated, but he faces a crowded Republican field. Top candidates include GOP Rep. Bradley Byrne, former Auburn football coach Tommy Tuberville, state Rep. Arnold Mooney and Alabama Secretary of State John Merrill. Former GOP Sen. Jeff Sessions, whose appointment as attorney general caused the 2017 special election, is also considering jumping into the race. Jones has continued his strong fundraising as Republicans fight it out, but it might not be enough to overcome the partisan dynamics in the state.

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The blue wave crashed into Colorado in 2018, with Democrats winning all five statewide executive offices and control of the state Legislature for the first time since 1936. Democrats think another wave could sweep Gardner out of office in 2020. They often note that 2018 GOP gubernatorial nominee Walker Stapleton got about 100,000 more votes than Gardner did when the latter narrowly won in 2014 — and still lost by 10 points. Former Gov. John Hickenlooper, who ended his presidential campaign to challenge Gardner, faces a Democratic primary challenge from former state House Speaker Andrew Romanoff. Hickenlooper, who has been endorsed by the Democratic Senatorial Campaign Committee, nearly matched Gardner’s fundraising in the most recent quarter, but the incumbent still had a cash-on-hand advantage.

McSally lost her first Senate run to Democrat Kyrsten Sinema in 2018, but was appointed after the election to serve part of the late Sen. John McCain’s term. She is running in 2020 to serve out the last two years of his term and she once again faces a well-funded opponent. Navy veteran and retired astronaut Mark Kelly has raised almost $14 million so far this year to McSally’s $8.5 million, a sign donors see him as a good bet for 2020. Kelly is married to former Arizona Democratic Rep. Gabrielle Giffords, who was shot and seriously wounded at a constituent event in 2011, and the couple has since campaigned across the country for stricter gun laws. Democrats are optimistic that the diversifying state, along with a candidate who can appeal to independent voters, gives them an opportunity to beat McSally again.

Running for his second term, Tillis faces battles on two fronts. First, he’s confronting a self-funding primary opponent in businessman Garland Tucker, who’s already forced the incumbent to reserve $2 million in TV ads to build his name recognition and strengthen his support with the conservative base. Even after flipping on Trump’s national emergency declaration on the southern border to side with the president, Tillis was booed at Trump’s most recent rally in the Tar Heel State. Army veteran Cal Cunningham looks like the front-runner on the Democratic side. Despite not being a well-known name in the state, the former state senator raised nearly as much as Tillis in the third quarter.

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Collins has long relied on her moderate, independent brand to dispatch previous challengers by double digits, but Democrats are hoping her vote for Kavanaugh and the difficulty of running with Trump on the ticket will help them finally pick up this seat. Collins hasn’t officially announced she’s running for a fifth term, but she’s been raising money like a candidate and had $7.1 million on hand as of Sept. 30. Still, state House speaker Sara Gideon, who has locked up much of the Democratic establishment support, outraised Collins, $3.2 million to $2.3 million in the third quarter. The eventual Democratic nominee will also be able to tap into $4 million donated by angry contributors after Collins’ Kavanaugh vote.

As one of only two Democratic senators running in a state Trump carried in 2016, Peters is a top GOP target. He’s likely facing 2018 GOP Senate nominee John James, an Army veteran who outraised Peters $3.1 million to $2.5 million in the third quarter. James lost to the state’s senior senator, Democrat Debbie Stabenow, by 6 points last year. Although Democrats concede Peters is less of an institution than Stabenow, his military background could mitigate some of James’ appeal. National Democrats have promised not to overlook Michigan as they did in the 2016 presidential race, which should help Peters, while James’ full embrace of Trump could backfire.

In her 2014 race, Ernst captured national attention by likening her experience castrating hogs to cutting government spending, pledging to “make ’em squeal” in D.C., and she is still popular and well-known in Iowa. But Democrats see an opportunity with Trump’s slipping approval ratings amid an ongoing trade war that has affected Iowa exports. Democrats also flipped two House seats in Iowa in 2018, which they see as a sign that Ernst could be in trouble. The DSCC and Iowa Democratic officials have backed real estate executive Theresa Greenfield to take on Ernst, but she still faces a primary.

With Democrats trying to make Georgia a presidential battleground, Perdue’s reelection (as well as the race for the state’s other Senate seat, being vacated by Republican Johnny Isakson for health reasons) should be competitive. But the Democratic field is still in flux. Jon Ossoff, who lost an expensive House special election in 2017, is well-known and can raise money but has baggage from that race, when he was tied to the national party. Still, Perdue has his work cut out for him in this demographically shifting state. He needs to turn out rural, conservative voters who are loyal to the president, while not turning off well-educated, suburban voters repelled by Trump.

Running in a presidential battleground that Clinton barely carried in 2016, the two-term senator should be at risk. But it’s not clear Republicans will have someone who can make this race competitive, and several of their candidates or potential ones, such as former Trump campaign manager Corey Lewandowski, could actually jeopardize their chances of beating Shaheen. National Republicans have been most excited about retired Brig. Gen. Don Bolduc, but he raised just $240,000 in the third quarter to the incumbent’s $2.3 million, and a late primary could make it difficult for the eventual GOP nominee to turn his attention to Shaheen.

A crowded field of Democratic contenders is vying to take on Cornyn, whose war chest was close to $10.8 million on Sept. 30. Despite Cornyn’s strong fundraising, Democrats think they can make the Texas Senate race competitive, particularly after former Rep. Beto O’Rourke came within 3 points of defeating GOP Sen. Ted Cruz in 2018. Some operatives argue that Cornyn will be a more difficult opponent than Cruz, whose national profile energized Democrats and turned off some Republicans. Democrats nationally rallied behind O’Rourke — that hasn’t happened for any of this cycle’s challengers yet. Still, Democrats are also hoping to flip a handful of GOP-held House seats in the Lone Star State, so their spending and organizing could affect Cornyn further up the ballot.

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