Below are a selection of races to watch ahead of the 2024 election.
ARIZONA: POSSIBLE THREE-WAY RACE
Senator Kyrsten Sinema, an independent who caucuses with the Democrats, has not yet declared whether she would seek reelection. But due to positions that have placed her odds with the progressive wing of the Democratic Party, Arizona may be set to have a rare three-way general election with Sinema, Democratic congressman Ruben Gallego and a Republican candidate.
The Republicans seeking the nomination include Kari Lake, who had been endorsed by former President Donald Trump during her unsuccessful 2022 run for governor, and Mark Lamb, a county sheriff.
MONTANA: VULNERABLE DEMOCRATIC INCUMBENT
Democratic Senator Jon Tester is seeking to defend his seat in a state that backed Republican former President Donald Trump during the 2020 election. Republican Tim Sheehy, a veteran who founded an aerial firefighting company, has filed to oppose Tester.
Republican U.S. Representative Matt Rosendale, who lost against Tester in 2018 and is one of eight Republicans who banded together to oust House Speaker Kevin McCarthy, is also expected to try to win the Republican nomination.
NEW JERSEY: LOOKING TO REPLACE MENENDEZ
Democratic Senator Bob Menendez so far has not said whether he will seek reelection after being indicted by federal prosecutors on bribery charges.
But multiple Democrats are eyeing the seat, including Tammy Murphy, the wife of Governor Phil Murphy; Representative Andy Kim; and progressive activist Patricia Campos-Medina.
OHIO: DEMOCRAT DEFENDING SEAT IN TRUMP-SUPPORTING STATE
Democratic Senator Sherrod Brown is seeking to defend his seat in a state that voted for Trump in the 2020 election. The race to win the Republican nomination so far includes Ohio's Secretary of State Frank LaRose; Matt Dolan, a state senator; and Bernie Moreno, a businessman.
PENNSYLVANIA: RETURN OF MCCORMICK
Republicans are eyeing the Pennsylvania U.S. Senate seat as a possible opportunity for them in the perennially competitive state. Democrat Bob Casey is running for reelection, where Dave McCormick, a former hedge fund executive, is vying for the seat.
McCormick had previously run for Senate in 2022, but lost the Republican primary to television personality Mehmet Oz, who had been endorsed by Trump. Oz went on to lose his race against Democrat John Fetterman.
UTAH: CROWDED REPUBLICAN PRIMARY
Utah is an open seat, with Republican Senator Mitt Romney, a prominent Trump critic and onetime party standard-bearer, announcing last fall that he would not seek re-election.
Unlikely to swing to Democratic hands, the state is expected to feature a crowded Republican primary. The candidates seeking the seat include the former speaker of the state's House of Representatives, Brad Wilson, U.S. Representative John Curtis, and Brent Orrin Hatch, the son of the senator who held the seat for 42 years before Romney.
(Reporting by Makini Brice; Editing by Scott Malone and Jonathan Oatis)
