The scenario long-dreaded by Republican strategists looks increasingly plausible following Tuesday’s primary election in Texas: Democrat James Talarico may face Republican Ken Paxton for the state’s U.S. Senate seat in November.

Paxton is heading for a runoff against Sen. John Cornyn where he is likely to be at least a slight favorite, though the final results from the first round of voting could shift expectations. Although Talarico has a 52% to 47% lead over Rep. Jasmine Crockett with roughly 70% of the vote in, according to The Associated Press, a final call may be complicated by a lawsuit seeking to extend voting hours in Dallas County.

Republicans fear the matchup could, at the very least, cost the party tens of millions of dollars to protect Paxton, the scandal-plagued Texas attorney general. A competitive race could give Democrats another pathway to the 51 seats they need to claim control of the Senate.

First, though, Paxton will have to defeat Cornyn in a May runoff. Speaking to reporters on Tuesday night, Cornyn warned that Paxton’s nomination would end three decades of GOP dominance in the state and take down-ballot Republicans with him in defeat.

“I’ve worked for decades to build the Republican Party, both here in Texas and nationally,” Cornyn said. “I refuse to allow a flawed, self-centered and shameless candidate like Ken Paxton to risk everything we’ve worked so hard to build over these many years.”