Billionaire Peter Thiel’s support for Arizona Senate candidate Blake Masters has now grown to $15 million as the venture capitalist and tech entrepreneur continued this month to pour money into the race to boost Masters’ cash-strapped campaign.

Thiel made an additional $1.5 million donation to the pro-Masters Saving Arizona super PAC on July 7, according to a Thursday filing with the Federal Election Commission. Masters’ own campaign has been significantly outspent on television by Republican primary opponent Jim Lamon, but the super PAC and other outside groups have spent heavily on his behalf to make up the gap. Masters has surged to the lead in public polling of the race for the GOP nomination with the help of Thiel’s super PAC funds and an endorsement from former President Donald Trump.

Masters is scheduled to appear at a rally with the former president Friday night in Prescott Valley, an event designed to boost several Trump-endorsed candidates who […]