One of the most bitter and expensive Senate races in Texas history is headed to a runoff between Sen. John Cornyn (R-TX) and Attorney General Ken Paxton.

Cornyn won 42.9% of the primary vote at the time the Associated Press called the race on Tuesday night, compared to 40.5% for Paxton. Neither candidate reached the 50% threshold needed to win the GOP nomination outright with 60% of votes counted, meaning voters will return for a May 26 runoff to decide who represents Republicans in the general election.