Every two years, one-third of the U.S. Senate is up for re-election. Here is a list of those who will be running in the 2018 elections.

Democrats

Baldwin, Tammy (D-WI)

Brown, Sherrod (D-OH)

Cantwell, Maria (D-WA)

Cardin, Benjamin L. (D-MD)

Carper, Thomas R. (D-DE)

Casey, Robert P., Jr. (D-PA)

Donnelly, Joe (D-IN)

Feinstein, Dianne (D-CA)

Gillibrand, Kirsten E. (D-NY)

Heinrich, Martin (D-NM)

Heitkamp, Heidi (D-ND)

Hirono, Mazie K. (D-HI)

Kaine, Tim (D-VA)

Klobuchar, Amy (D-MN)

Manchin, Joe, III (D-WV)

McCaskill, Claire (D-MO)

Menendez, Robert (D-NJ)

Murphy, Christopher (D-CT)

Nelson, Bill (D-FL)

Stabenow, Debbie (D-MI)

Tester, Jon (D-MT)

Warren, Elizabeth (D-MA)

Whitehouse, Sheldon (D-RI)

Republicans

Barrasso, John (R-WY)

Corker, Bob (R-TN)

Cruz, Ted (R-TX)

Fischer, Deb (R-NE)

Flake, Jeff (R-AZ)

Hatch, Orrin G. (R-UT)

Heller, Dean (R-NV)

Wicker, Roger F. (R-MS)

Independents

King, Angus S., Jr. (I-ME)

Sanders, Bernard (I-VT)