Texas Attorney General Ken Paxton, who was endorsed by President Donald Trump, will defeat incumbent Sen. John Cornyn in the Republican Senate primary runoff, CNN’s Decision Desk projects.

The Republican primary for U.S. Senate reached an end on Tuesday as voters picked Paxton to take on Democrat James Talarico in the midterms.

The Texas primary runoffs are over and November election matchups are set in major contests, like one for the U.S. Senate, as the results deliver lessons for both parties.

Democratic and Republican primary candidates whose races were too close to call in March are vying for voter approval Tuesday as they seek spots on the November ballot. Follow along for live updates.

Sen. John Cornyn’s (R-TX) performance in the Texas Senate GOP primary election on Tuesday indicated polling for one of the country’s most closely watched races failed to sufficiently capture the political dynamic.

The most expensive primary runoff in recent history is being held Tuesday in Texas, where Republicans are deciding whether to nominate Senator John Cornyn, a mainstay with 23 years in office, or to oust him in favor of his MAGA-aligned challenger, Ken Paxton, the Texas attorney general.

Texas' runoff primary elections are Tuesday. The race generating the most attention – and money – is the Texas Republican U.S. Senate primary between incumbent Senator John Cornyn and Texas Attorney General Ken Paxton.