Looking ahead to 2018, the numbers clearly work for the Republicans in Senate elections to retain and even expand their majority. There are 25 Democratic (including two independents) seats up for election and only eight for the Republicans.
Most of the eight Republican seats look safe for the incumbents. A number of the Democrats have to run in states that went for Donald Trump in 2016.
Those Democratic Senators running in states carried by President Trump by double digits include Joe Donnelly in Indiana, Claire McCaskill in Missouri, Jon Tester in Montana, Heidi Heitkamp in North Dakota and Joe Manchin in West Virginia.
On the other hand, mid-term elections can be hard on the party in power, which almost always loses seats. Midterm elections tend to be referenda on the incumbent presidents; if Donald Trump proves divisive and controversial and stumbles in office, there may be an opening for Democrats.
Another thought worth considering is that as of January 2017, no incumbent Senator has announced their retirement. That may change in the coming months.
Senators up for re-election in 2018
California – Dianne Feinstein (D)
Connecticut – Chris Murphy (D)
Delaware – Tom Carper (D)
Florida – Bill Nelson (D)
Hawaii – Mazie Hirono (D)
Indiana – Joe Donnelly (D)
Maine – Angus King (I)
Maryland – Ben Cardin (D)
Massachusetts – Elizabeth Warren (D)
Michigan – Debbie Stabenow (D)
Minnesota – Amy Klobuchar (D)
Missouri – Claire McCaskill (D)
Montana – Jon Tester (D)
New Jersey – Bob Menendez (D)
New Mexico – Martin Heinrich (D)
New York – Kirsten Gillibrand (D)
North Dakota – Heidi Heitkamp (D)
Ohio – Sherrod Brown (D)
Pennsylvania – Bob Casey, Jr. (D)
Rhode Island – Sheldon Whitehouse (D)
Vermont – Bernie Sanders (I)
Virginia – Tim Kaine (D)
Washington – Maria Cantwell (D)
West Virginia – Joe Manchin (D)
Wisconsin – Tammy Baldwin (D)
Arizona – Jeff Flake (R)
Mississippi – Roger Wicker (R)
Nebraska – Deb Fischer (R)
Nevada – Dean Heller (R)
Tennessee – Bob Corker (R)
Texas – Ted Cruz (R)
Utah – Orrin Hatch (R)
Wyoming – John Barrasso (R)
An early look at specific 2018 races
Arizona: Sen. Jeff Flake (R) has been an ardent and vocal opponent of Donald Trump. Ex-state Sen. Kelli Ward (R), who lost last year’s primary to Senator McCain 51%-40%, announced that she would challenge Flake, but other opponents are likely to emerge. Democrats have not been successful statewide in recent years.
Florida: Governor Rick Scott (R), who is term limited may challenge Senator Bill Nelson in what would be a very expensive and competitive race. Nelson, who is 74, is the most popular politician in Florida, but Scott has won the governorship twice and is very wealthy. President Trump, a good friend of Scott, has been encouraging the governor to run.
Maine: Gov. Paul LePage (R), a two-term governor who is infamous for his controversial remarks, has suggested he may challenge Sen. Angus King (I). If so, it could be a barn burner.
Massachusetts: Former Boston Red Sox pitcher Curt Schilling (R), a hero to many Massachusetts voters, has suggested he may challenge Sen. Elizabeth Warren (D). Rick Green (R), a wealthy businessman and founder of the Massachusetts Fiscal Alliance, may also run.
Missouri: Sen. Claire McCaskill (D) was fortunate to run against Rep. Todd Akin (R), who made infamous comments about “legitimate rape.” Rep. Ann Wagner (R) may challenger McCaskill.
Montana: Sen. John Tester (D) dodged a bullet when Rep. Ryan Zinke (R), who represents the entire state in the House, was appointed Interior Secretary. But Trump carried the state by 20%, so Tester’s re-election will not be easy.
Ohio: Sen. Sherrod Brown (D) beat back a challenge in 2012 from state treasurer Josh Mandel (R), but Mandel is planning a return engagement. Mandel may have competition for the Republican nomination from Rep. Pat Tiberil.
Nevada: Senator Dean Heller (R) is up for election in a state carried twice by President Obama and once by Hillary Clinton. Still, Heller has won four elections in the state and he will not be easy to dislodge.
Wisconsin: A lot of Republicans are circling around the seat of Sen. Tammy Baldwin (D), including State Senate Majority Leader Scott Fitzgerald (R), Rep. Sean Duffy (R), state Sen. Leah Vukmir (R), businessman Eric Hovde (R) and Marine veteran Kevin Nicholson (R).