Texas Republicans cast ballots Tuesday in a Senate primary runoff between incumbent Sen. John Cornyn and state Attorney General Ken Paxton, a race that analysts say could reshape the balance of power in Washington.
The contest has been called the most expensive Senate primary in history. It follows a March 3 primary in which Cornyn led the field but failed to secure 50 percent of the vote, triggering the runoff. No Democrat has won statewide office in Texas since 1994, meaning whoever wins Tuesday is widely expected to win in November.
The race shifted dramatically when President Trump endorsed Paxton six days before election day, one day after early voting began. Trump had withheld his endorsement for weeks after the March primary, briefly saying he would endorse "SOON" and calling on whichever candidate he did not choose to drop out. Paxton, meanwhile, said he would only withdraw if the Senate passed the SAVE America Act, a voter ID bill backed by Trump.
Rice University political science professor Mark Jones described the impact of the late endorsement. "The moment Donald Trump endorsed Ken Paxton, he took a somewhat unlevel playing field and turned it into a steep cliff," Jones said, according to CBS News.
Trump's endorsements have been decisive in other recent Republican contests. In Louisiana, he endorsed Sen. Bill Cassidy's opponent, and Cassidy failed to advance to the runoff. In Kentucky, Rep. Thomas Massie, a frequent Trump critic, lost to a Trump-backed challenger.
Cornyn, first elected in 2002, served as Republican whip and chaired the Senate GOP fundraising arm. He was viewed by many Republicans as a stronger general election candidate against Democrat James Talarico, who won his party's March primary. The Senate Republican fundraising operation spent millions opposing Paxton in the runoff, and party strategists have warned that a Paxton nomination would require additional spending in the fall given his weaker fundraising record.
Paxton, who has been a staunch Trump supporter for years, was first elected Texas attorney general in 2014. Several other races are also on Tuesday's runoff ballot, including the attorney general's race, state railroad commissioner, and a number of congressional contests.
