While the Democratic Party hopes to capitalize on its victory in the Alabama special election to win back control of the Senate, the sheer number of seats they must defend, especially in states won by President Trump in 2016, makes the prospect of wresting back control of the Senate a significant challenge at best.
Heading into the 2018 midterms, Republicans hold a slim 51-47 majority, with the remaining two seats held by independents who caucus with the Democrats. Democrats are poised to defend 25 seats (including both independents), while Republicans must defend eight.
While the lopsided number of contested seats held by Democrats compared to those held by Republicans is a tough obstacle for Democrats to overcome, they are further burdened by having to defend 10 seats in states won by President Trump in 2016.
In sharp contrast, Republicans are defending only one seat in a state won by Hillary Clinton. The National Republican Senatorial Committee (NRSC) raised $41.5 million in 2017 – the most it’s ever raised during a non-election year.
It is likely control of the Senate will be decided by 12 key races.
Arizona (Toss-Up, Retiring Republican Incumbent)
Republican Senator Jeff Flake, a staunch opponent of President Trump, has announced he will not seek re-election. While no Democrat has represented Arizona in the Senate for over 20 years, shifting demographics make the state one of the Democrats’ best opportunities for a pickup.
Democrats are rallying behind Representative Kyrsten Sinema, who is openly bisexual and a self-described atheist.
The Republican primary is set to be a bruising battle between the party establishment’s preferred candidate, Representative Martha McSally, and populist outsiders, including former Maricopa County Sheriff Joe Arpaio and former State Senator Kelli Ward, who unsuccessfully challenged Senator John McCain in the 2016 Republican primary.
While Trump won Arizona by nearly 3.5 percent, it was a sizable decline from Mitt Romney’s 9 percent margin of victory over Obama in 2012, demonstrating the state’s shift towards the Democratic Party in the face of a rapidly growing Hispanic population.
Florida (Toss-Up, Democratic Incumbent Seeking Re-Election)
Incumbent Senator Bill Nelson is one of ten Democrats seeking re-election in a state won by President Trump. While Nelson handily won re-election in 2012, he is now the only Democrat to hold statewide office.
While numerous Republicans have already declared their candidacies, most are holding out hope that term-limited Governor Rick Scott will enter the race. Early polls already show Scott tied with Nelson, or leading outright.
Indiana (Toss-Up, Democratic Incumbent Seeking Re-Election)
Senator Joe Donnelly is another Democrat unfortunate enough to be running for re-election in a state handily won by President Trump, making Indiana one of the Republican Party’s best opportunities to flip a seat.
The two top candidates vying for the Republican nomination are Representatives Luke Messer and Todd Rokita.
Maine (Leans Independent, Incumbent Independent Seeking Re-Election)
Senator Angus King, an independent who caucuses with the Democrats, is running for re-election in a state Hillary Clinton carried by around three percent. Due to Maine’s unique process (one shared with Nebraska) that awards electoral votes based on which candidate wins each of the state’s congressional districts, President Trump received one electoral vote from the state’s 2nd Congressional District – becoming the first Republican to do so since 1988.
While the only declared Republican candidate thus far is State Senator Eric Brakey, who has been endorsed by Kentucky Senator Rand Paul and former Texas Representative Ron Paul, President Trump has reportedly urged outgoing Governor Paul LePage to challenge King.
Missouri (Toss-Up, Democratic Incumbent Seeking Re-Election)
President Trump carried Missouri by over 18 percent in 2016, leaving incumbent Senator Claire McCaskill incredibly vulnerable as she seeks re-election. McCaskill’s re-election campaign in 2012 was the last time a Democrat won statewide office in Missouri.
Republicans are rallying around State Attorney General Josh Hawley, who will face numerous candidates in the party’s primary, including Austin Petersen- a failed candidate for the Libertarian Party’s nomination for president in 2016.
Montana (Lean Democratic, Incumbent Democrat Seeking Re-Election)
Democratic Senator Jon Tester is running for re-election in a state President Trump carried by over 20 percent, making Montana a prime target for Republicans.
Tester, who won his first term by one percent and his second term in 2012 by less than four percent, has already attracted a large field of Republican challengers, including State Auditor Matt Rosendale, businessman Troy Downing, and State Senator Albert Olszewski.
Nevada (Toss-Up, Incumbent Republican Seeking Re-Election)
Republican Senator Dean Heller has the dubious distinction of being the only Republican Senator running for re-election in a state carried by Hillary Clinton. Shifting demographics has turned the once purplish-red state blue, making Nevada one of the Democratic Party’s most prime opportunities for a pick-up.
First-term Representative Jacky Rosen and attorney Jesse Sbaih are the two most likely Democratic challengers.
Heller, who won his first term in 2012 by less than one percent, must first get through his party’s primary, where he faces insurgent populist candidate Danny Tarkanian.
North Dakota (Leans Democratic, Incumbent Democrat Seeking Re-Election)
President Trump won North Dakota by a staggering 35.7 percent, leaving Democratic Senator Heidi Heitkamp vulnerable as she seeks re-election. Despite her vulnerability, however, no high-profile Republican has declared their candidacy.
State Senator Tom Campbell is the only declared candidate thus far after the state’s at-large Representative Kevin Cramer announced he will not enter the race. Former Representative Rick Berg, who lost to Heitkamp by less than one percent in 2012, could also enter the race.
Ohio (Leans Democratic, Incumbent Democrat Seeking Re-Election)
After being labeled a toss-up throughout the 2016 presidential campaign, President Trump went on to handedly carry the Buckeye State by over eight percent. The state’s incumbent Senator, Sherrod Brown, is now Ohio’s sole Democrat elected to statewide office.
The previous Republican front runner, State Treasurer Josh Mandel, recently dropped out of the race citing issues related to his wife’s health, leaving the party without a high-profile candidate until Representative Jim Renacci entered the race.
Renacci had previously declared his intention to run for Governor to replace term-limited Republican John Kasich.
Pennsylvania (Leans Democratic, Incumbent Democrat Seeking Re-Election)
President Trump pulled off an upset when he defeated Hillary Clinton and became the first Republican presidential candidate to carry Pennsylvania since 1988, leaving incumbent Democratic Senator Bob Casey vulnerable.
Representative Lou Barletta is the font-runner for the Republican nomination.
Tennessee (Leans Republican, Incumbent Republican Retiring)
Senator Bob Corker, who transitioned from an ally of President Trump to one of his harshest critics, announced he will not seek re-election. Democrats, using their special election victory in Alabama as justification, believe they can flip Tennessee with the candidacy of former Governor Phil Bredesen.
Representative Marsha Blackburn is the likely Republican candidate.
West Virginia (Toss-Up, Democratic Incumbent Seeking Re-Election)
West Virginia gave President Trump his largest margin of victory over Hillary Clinton (42.2 percent), leaving Senator Joe Manchin incredibly vulnerable.
The Republican primary will feature another campaign between the party establishment, represented by Representative Evan Jenkins, and the populist wing, represented by State Attorney General Patrick Morrisey.