Moderate mayor wins Republican primary to replace Rep. Chaffetz in Utah

John Curtis, the mayor of Provo, Utah, won the Republican primary in his state's third congressional district Tuesday, capping a campaign that will see him advance to November's general election after he collected over 15,000 signatures from party members simply to make the primary ballot.

The Associated Press projected Curtis to be the winner at 11:45 p.m. ET with 77 percent of precincts reporting.

Curtis' victory comes in the course of the district's special election to replace Rep. Jason Chaffetz who officially resigned from his seat in May. He will face Democrat Kathie Allen and a collection of third party candidates in the general election on November 7.

The heavily conservative district, which Chaffetz represented from 2008 until this year, is widely expected to remain in Republican hands, but voters across Utah have previously registered their hesitations about President Donald Trump, who failed to receive a majority of the vote in the district in 2016, and earlier lost the statewide caucus to Sen. Ted Cruz, R-Texas, by a wide margin. Curtis admitted during his campaign to having not voted for Trump in November.

Former Utah state Rep. Chris Herrod finished second to Curtis Tuesday. Herrod secured the Republican nomination for the seat via the party's convention, but still faced a primary challenge after Curtis and businessman Tanner Ainge collected enough signatures to earn a spot in the race, according to The Salt Lake Tribune

While Curtis' campaign had its roots in the signature-collection effort, he received a number of high profile endorsements in recent weeks to bolster his reputation, including from Utah Gov. Gary Herbert and the Tribune, the state's largest newspaper. Despite that support, Curtis has faced questions about his conservative credentials. Curtis once headed a county Democratic party committee, and was a registered Democrat until 2006, when he switched his registration to Republican.

He has served as mayor of Provo, the district's largest city and home to Brigham Young University -- the alma mater of all three of Tuesday's candidates -- since 2010.

Herrod had the backing of two sitting U.S. senators, Sen. Rand Paul, R-Ky. and Sen Ted Cruz, R-Texas, the latter for whom Herrod worked as Utah state director during the 2016 presidential race.

Ainge, the son of Boston Celtics General Manager Danny Ainge ,who is well known in Utah for his time as a college basketball player at BYU, was the political newcomer of the group, though had earned the support of 2008 Republican vice presidential nominee Sarah Palin.

Chaffetz resignation in the Spring took some in the Republican party by surprise. Thought to be a rising star in the party, the representative made a name for himself as the chairman of the House Oversight Committee and gained political visibility after the panel pursued aggressive investigations of former Secretary of State Hillary Clinton, the Internal Revenue Service and former Attorney General Eric Holder.

In November, Chaffetz won reelection to his fifth term by a 73.5 to 26.5 percent margin over his Democratic competitor. The winner of the general election this November will complete Chaffetz's term and be up for reelection in 2018.

ABC News' Dakshayani Shankar contributed to this report.