Karrin Taylor Robson, a wealthy Republican businessperson who was seen as the likeliest establishment candidate for a crucial Arizona Senate contest, said Thursday that she won't run for the seat now held by independent Kyrsten Sinema.

Robson ran for governor last year but lost the GOP primary to Kari Lake, a Donald Trump ally and darling of his Make America Great Again movement. Lake went on to lose the general election to Democrat Katie Hobbs and said this week she is considering a run for Senate.

The Arizona Senate race is a pickup opportunity for the GOP, but many traditional Republicans worry Lake, who would be the clear front-runner in a GOP primary, can't win a general election.

Sinema left the Democratic Party last year. She is raising money for a potential campaign but has not said whether she will seek a second term, a decision that could set up a complicated three-way contest. U.S. Rep. Ruben Gallego is the only major Democratic candidate in the race so far.

Robson said she may run for office in the future but “now is not the time.” She said she’ll instead work to “identify and elect strong conservatives,” focusing in particular on the state Legislature where Republicans hold a narrow majority.

“Arizona voters will help determine control of the U.S. Senate in 2024, and it has been humbling to hear from Arizonans around this state who have urged me to enter this race,” Robson said in a statement announcing her decision.

Robson, a lawyer for housing developers, spent millions from her family's vast fortune on her unsuccessful campaign for governor last year. She racked up endorsements from prominent establishment Republicans including then-Gov. Doug Ducey and former Vice President Mike Pence.

Read More