MINNEAPOLIS — Democratic Rep. Tim Walz won Tuesday’s open election for Minnesota governor, defeating second-time Republican candidate Jeff Johnson to extend Democrats’ hold on the state’s top executive office.

After campaigning to expand the state’s low-income health care program with a public option and increase public school funding, Walz said his victory was proof that voters are ready for those policies. And he relished massive turnout that helped power Democrats up and down the ballot.

“That can-do spirit in Minnesota is alive and well. I can feel it through this,” Walz said.

It was the first open governor’s race since 2010, when Democratic Gov. Mark Dayton won the first of his two terms. Dayton opted not to run for a third term, setting off a wide-open race to replace him.

Walz was the heavy favorite throughout the race, holding large leads over Johnson in public polling. But his victory was still an oddity: It was the first time one of Minnesota’s political parties has held on to the office for three or more terms since the 1950s.

While Johnson portrayed his own candidacy as a course correction after the Dayton administration, Walz vowed to continue the liberal path that Dayton began during his two terms. Expanding the state’s low-income health care program, MinnesotaCare, to have a public option was a hallmark of his campaign. But he drew criticism from both sides for his tepid support of a $15 hourly minimum wage, despite campaigning for it earlier in the election cycle.

At a polling place near the University of Minnesota in Minneapolis, several voters said Walz, a former high school teacher, was one of their biggest motivations for voting.

“Tim Walz has the answers,” said Dennis Draughn, 33, who teaches at suburban Apple Valley High School.

Desiree Richardson, 25, a teacher in the Minneapolis Public Schools system, said Walz’s platform resonated with her, too.

“He wants to back the schools. So that’s a big one because I work in the school system, so I want somebody that’s going to back me,” she said.

Walz will move up to the state’s top office after six terms in Congress, where he represented the conservative-leaning 1st District in southern Minnesota. He used his appeal in rural areas to promote a theme of “One Minnesota” and enlisted a popular liberal activist and lawmaker, Rep. Peggy Flanagan, as his running mate. He also brought mayors from Fergus Falls to Golden Valley onboard to support the campaign.

Johnson, a Hennepin County commissioner known for often being a lonely conservative voice on that body, was the GOP’s losing candidate against Dayton in 2014. But Johnson had already surprised once, handily beating former Gov. Tim Pawlenty in the primary despite being outraised several times over.

But the Republican Governors Association, a major outside political group that backed Pawlenty, balked at Johnson’s candidacy, backing away from a $2.3 million advertising blitz that had been planned for summer and fall. It never aired an ad on Johnson’s behalf.

Johnson accused Walz of overpromising, and deemed his health care plan unworkable for hospitals that are reimbursed by the state at lower rates than private health insurers.