By Neil Vigdor

In a repudiation of the GOP's nominating process for governor, outsider Bob Stefanowski became the first petition candidate in Connecticut history to win a major party's nomination for statewide office Tuesday, besting the endorsed Republican, longtime Danbury Mayor Mark Boughton.

The former UBS Investment Bank chief financial officer skipped the state GOP convention in May and most of the party-organized debates earlier this year.

Stefanowski, 56, a Madison resident, instead saturated the television airwaves early to introduce himself to Republicans and petitioned his way onto the ballot in the five-way primary.

The strategy paid enormous dividends for Stefanowski, who capped off a 19-hour day with a victory speech at the Madison Beach Hotel. All four of his opponents conceded by 10:30 p.m., with Boughton the last domino to fall.

Boughton trailed Stefanowski by more than 10,000 votes with 80 percent of precincts reporting, with turnout surpassing 2010 and 2014 totals. Hedge fund mogul David Stemerman, who spent $6 million of his own money on an avalance of attack ads and army of political operatives finished third. Former Trumbull First Selectman Tim Herbst was fourth and Westport tech entepreneur Steve Obsitnik was fifth.

"So I think it's fair to say this campaign has been underestimated from the start," Stefanowski said. "I don't think anybody really thought we would be standing up here right now. We've proved them wrong and we're going to prove them wrong when we beat Ned Lamont in November."

In the race for lieutenant governor, conservative state Sen. Joe Markley of Southington defeated New Britain Mayor Erin Stewart and Darien First Selectman Jayme Stevenson.

Do the state's 400,000 registered Republicans entrust their nomination to an insider who has previously held elected office or does it turn over the reins to an outsider from the business world -- like national Republicans did in 2016 with Donald Trump?

"I think higher [turnout] is always better," Stefanowski said outside North Street School in Greenwich, his first campaign stop of primary day.

Stefanowski built an early lead Tuesday night in eastern Connecticut, where Herbst had focused significant time and resources in rural areas. But Stefanowski also appeared to be holding his own in Fairfield County, a potentially ominous sign for the party favorite, Boughton.

Boughton overwhelmingly held serve in Danbury, where he's been mayor for 17 years. The burning question for the social media-savvy former state legislator and history teacher is a 2,000-vote edge in the Hat City enough to offset Stefanowski's pickups across the state?

All three political outsiders outperformed the traditional politicians in Greenwich, with Stemerman, Obsitnik and Stefanowski finishing in the top-three in the GOP bastion that was the boyhood home of former President George H.W. Bush, according to unofficial results.

In Shelton, another Fairfield County battleground, Stefanowski rolled to a 3-to-1 advantage over Boughton, according to the city's longtime mayor, Mark Lauretti, who last month endorsed Stefanowski after a falling out with Boughton.

This is the third run for governor for Boughton, 54, who has cast himself as a blue-collar Republican who has insulated the state's seventh-largest city from the economic and crime woes of many of Connecticut's urban centers.

It's been 53 weeks since Boughton had major surgery to remove a non-cancerous brain tumor, which raised concerns about his health, along with his collapse at a GOP event in March in Avon. Boughton says he's headache and has no restrictions. Saying he's "just happy to be here" outside Cheshire High School, his final campaign stop on primary day, Boughton commented that he's been proving people wrong throughout the race.

"People didn't think I could raise the money. We did," Boughton said. "They didn't think we'd take the convention. We did. They didn't think I'd be re-elected mayor. I was. I'm feeling great."

The perception going into Tuesday was that Boughton's biggest threats were from Stefanowski and Herbst, a former Trumbull first selectman.

Stemerman tried to make a late surge in the race, spending $6 million of his fortune on cadre of political operatives and a blitz of attack ads, a number of them targeting Stefanowski.

The two businessmen missed each other by five minutes at in Greenwich, where Stemerman cast his ballot at 7 a.m.

"It's interesting that he actually knows where a voting booth is," Stemerman said sarcastically after voting, referring to a 17-year gap in voting by Stefanowski.

Steve Obsitnik. a Westport tech entrepreneur, was expected to siphon off some Fairfield County votes, but delays in his public campaign financing hobbled his candidacy after a third-place convention finish.

Herbst, who narrowly lost his 2014 bid for state treasurer, finished second to Boughton for the endorsement at the state GOP convention in May. The 37-year-old Trinity College graduate has staked out the party's right flank, securing the endorsements of the pro-gun Connecticut Citizens Defense League and the pro-life Family Institute of Connecticut.

Courant staff writers Josh Kovner, Kathleen Megan, Matthew Ormesth and Alison Kuznitz contributed to this story.

(c)2018 The Hartford Courant (Hartford, Conn.)