ROCHESTER – A punishing 10-ballot contest spanning two days ended Saturday with businessman Mike McFadden sweeping his opposition to capture the Republican Party endorsement for a U.S. Senate seat, setting up the political newcomer to take on Democratic Sen. Al Franken in November.

The investment banker won the endorsement in a contest that started Friday, deadlocked at 2 a.m., then resumed midmorning. McFadden outmaneuvered more seasoned political veterans and overcame an unexpected surge by Republican Chris Dahlberg, a St. Louis County commissioner who made a surprisingly strong showing.

Hoarse, with his shirtsleeves rolled up, the newly endorsed McFadden told delegates: "We will fight and we will win, and in November we will beat Al Franken. We will turn this back into a red state."

In the end, McFadden's superior fundraising and extensive campaign organization trumped Dahlberg's outsider appeal and claims of electability in DFL-leaning northern Minnesota.

McFadden initially suffered with delegates for his refusal to abide by the party endorsement, which Dahlberg promised to honor. But the dynamic shifted in the light of morning, as legions of white- and orange-shirted McFadden volunteers swarmed the convention floor to lobby delegates.

McFadden also scored a coup in landing the endorsement of retiring U.S. Rep. Michele Bachmann, who remains an influential force among Republican activists. She called McFadden the only contender with a viable shot at unseating Franken.

'Reality set in'

"Dahlberg was the underdog and the novelty," said Ken Cobb, a delegate and insurance agent from Bemidji who supported McFadden. "But after people slept on it, they started thinking about it in terms of reality and not novelty. Reality set in and I think delegates wanted a candidate who was better organized and better able to mount a statewide effort."

Keith Kiefer, a Sherburne County delegate and a retired engineer, was still supporting Dahlberg on Saturday morning but said the lobbying from McFadden staffers was "intense."

"I admit I was impressed by the exuberance," Kiefer said. But he continues to worry that McFadden is not a true conservative and would move left on some issues as the general election approaches. "I don't think he's someone who's going to take on the status quo," Kiefer said.

In his last speech to the convention prior to winning the endorsement, McFadden defended his conservative credentials. He called himself a staunch defender of gun rights and a committed opponent of legal abortion.

"We believe in a culture of life," McFadden said. "From the womb to the last breath, it has to be protected."

After his win, McFadden pivoted to an economic message that he indicated would be the basis of his campaign.

"I've created jobs. That's what I do," McFadden said. "I look forward to that conversation."

Franken also picked up his endorsement from DFL activists Saturday, at their party convention in Duluth. For months, the Minnesota DFL and allied groups have been beating up on McFadden. They've keyed in on his work as CEO of Lazard Middle Market, a Twin Cities investment firm, which has led liberal groups to paint him as similar to 2012 Republican presidential candidate Mitt Romney.

In a news release, the DFL described McFadden as a candidate "masked in platitudes and poll-tested talking points."

McFadden wasn't shy about boasting of his fundraising prowess, noting his $1.85 million in the campaign bank dwarfed the fundraising of the other Republican candidates combined. His personal wealth could also be a resource.

Franken had nearly $6 million banked for the campaign, according to recent campaign finance records. His fundraising strength has reduced perceptions of his vulnerability this year, but nationally this election cycle has been predicted to be a tough one for Democrats.

McFadden's campaign is led by paid political veterans, and he has close ties to Republican establishment figures in both Minnesota and Washington, D.C. One of his earliest supporters was former Sen. Norm Coleman, whom Franken narrowly beat in 2008 in a contest that led to a recount.

While McFadden had not been favored to win, campaign manager Brad Herold said the campaign poured huge resources into securing the endorsement. In recent months volunteers made more than 50,000 phone calls to several thousand potential convention delegates, he said.

Even as McFadden's voice flagged, the energy of his forces grew. The father of six employed several of his older kids as surrogates, and his appearances on the stage were punctuated by aggressive rock and hip-hop tunes.

There is still a chance McFadden could face a primary challenge from state Rep. Jim Abeler, who sought the GOP endorsement but was eliminated in Friday's early rounds of voting. Abeler said Saturday he would take the weekend to decide whether to continue his candidacy.

McFadden, married with five sons and a daughter, lives in the St. Paul suburb of Sunfish Lake. Herold said he'd take a day off the campaign trail on Sunday for his daughter's graduation from Convent of the Visitation High School in Mendota Heights.

Rachel E. Stassen-Berger and Abby Simons contributed to this report.

Patrick Condon • 651-925-5049