Blake Masters, protege to billionaire tech investor Peter Thiel, has won the Arizona’s Republican nomination for US Senate late Tuesday night, the Associated Press and New York Times are reporting.

Masters’ triumph over solar power executive Jim Lamon installs the Trump-endorsed candidate as the GOP’s choice to take on former NASA astronaut Sen. Mark Kelly (D) this fall. Arizona is one of a handful of toss-up races that could decide which party controls the Senate come November.

Prior to Masters’ campaign announcement last summer, Politico reported that controversial tech investor Thiel funneled millions into the new Saving Arizona PAC in anticipation of his pupil’s Senate race. Thiel has donated at least $15 million to the PAC as of election day, according to campaign finance records.

Much of the PAC’s funding has gone towards a wave of negative ads attacking Lamon and opponent Attorney General Mark Brnovich, who drew criticism from Trump for not doing enough to investigate false allegations of voter fraud in Arizona. On Monday, Brnovich released a report identifying that his office found no evidence of widespread voter fraud in 2020.

With Masters’ Tuesday win, both of Thiel’s favored Republican Senate candidates successfully beat out their primary competitors this cycle. J.D. Vance, a longtime friend to Thiel and Hillbilly Elegy author, won the Republican Ohio Senate primary this past May. Thiel put $15 million into a pro-Vance super PAC, over the last year. If Masters and Vance go on to win their November general elections, they would bring newly tech-inspired ideologies to the Senate, both strongly inspired by Thiel and endorsed by Trump.