Most of the state’s big GOP donors are backing U.S. Sen. John Cornyn through the Super PAC Texans for a Conservative Majority, which had raised $18.5 million as of Dec. 31. Cornyn is seeking to fend off challenges from fellow Republicans Attorney General Ken Paxton and U.S. Rep. Wesley Hunt.

A Super PAC backing Paxton, known as Lone Star Liberty PAC, has raised $3.9 million from donors not as well known in Texas GOP circles.

And little is known about who is backing Hunt, who is getting support from a dark money group not required disclose its finances. Dark money groups are also helping boost Cornyn and Paxton, and the big contributors behind those efforts are unknown.

On the Democratic side, U.S. Rep. Jasmine Crockett of Dallas is locked in a tight race with Austin state Rep. James Talarico.

A mix of celebrities and well-heeled socialites from Houston and Austin are funding the Super PAC supporting Talarico, Lone Star Rising, which has raised close to $400,000 since launching in September.