Gov. Greg Abbott endorsed her opponent, Patrick Gurski.
Dan Patrick endorsed Schatzline, while Greg Abbott endorsed his opponent.
Christian defeated oil and gas attorney Sarah Stogner.
More than 20 states have already made plans to leave the national organization, after a letter was sent to the Justice Department labeling parents as “domestic terrorists.”
These groups have long opposed school choice and other forms of education reform.
Abbott’s last 30-day extension is set to expire on Sunday, May 22.
“Unlike in most states, the Texas GOP is not merely just a cheerleading society for elected officials.”
Runoff elections have historically been perilous territory for incumbent lawmakers in Texas.
Sarah Stogner previously said she would self-fund her campaign.
New polling of Republican primary voters shows Paxton leading with 58 percent.