J.D. Vance

Author J.D. Vance emerged from a crowded Republican primary in Ohio, and now becomes the favorite in the general election in the GOP-leaning state.

This month's primaries and runoffs will serve as a test of the power of former President Donald Trump's endorsements up and down the ballot.

The endorsement could buoy the Hillbilly Elegy author's chances in a crowded GOP primary field.

Though more Republican-held seats are up for grabs in November, Democratic struggles mean the GOP has improved its likelihood to take control of the Senate. Here are the key contests to watch.

The lack of a Trump endorsement hasn't stopped individual Republican candidates from selling themselves to voters as the most Trump-like in the primary.