MINNEAPOLIS — In central Minnesota, Republican Tom Emmer stepped into the congressional seat being vacated by Michele Bachmann, rejuvenating his political career just four years after a narrow defeat in the governor’s race.

Emmer eased past Democrat and Sartell Mayor Joe Perske and Independence Party candidate John Denney, a law student, for the central Minnesota seat held by Bachmann, who is retiring. Emmer lost the governor’s race four years ago to Democrat Mark Dayton.

Rep. Rick Nolan fended off a strong challenge Tuesday from Republican hopeful Stewart Mills, hanging onto his northeastern Minnesota seat in the U.S. House for a second term.

Nolan’s victory caps off a big day for Minnesota Democrats, who protected incumbents in tight re-election bids that prompted millions of dollars in outside spending. In northwestern Minnesota, 12-term Rep. Collin Peterson beat Republican state Sen. Torrey Westrom.

“When reports came out that the campaign was in trouble, people stepped up in ways I have never seen before. There was just an incredibly powerful groundswell of support,” Nolan told The Associated Press after addressing supporters in Baxter.

Mills spokeswoman Chloe Rockow said Mills didn’t plan to call Nolan to concede until after all election results were fully counted.

Firm leads in Democratic strongholds of the massive 8th District powered Nolan to re-election in his second stint in Congress — he also served in the House in the 1970s and early ‘80s. Nolan attributed his win to top-of-the-ticket help from Gov. Mark Dayton and U.S. Sen. Al Franken, as well as the Democratic party’s renewed focus on turnout in the 8th District after longtime incumbent Rep. Jim Oberstar’s shocking loss in 2010.

Elsewhere, Democrats in the Twin Cities metro and southern Minnesota and Republicans in suburban districts cruised to re-election.

Mills, a 42-year-old scion of the Fleet Farm chain of stores, had hoped to capitalize on the 8th District’s changing political face. He weathered attack ads from Democratic groups targeting his personal wealth — and his chin-length hair — in a race that topped the $10 million mark for outside spending.

Mills called for a “flatter, fairer” tax code and criticized Nolan for supporting President Barack Obama’s health care overhaul, as well as votes to ban assault weapons and on other gun control measures.

Nolan, 70, defended his stance on guns, saying he doesn’t need an assault rifle to go hunting. He also played up a middle-class ethos in the waning days of his campaign. He, too, was the subject of millions of dollars of attack ads from outside groups.

Peterson, who has mostly coasted through previous re-election campaigns, got a first taste of outside money in the massive 7th District. Peterson faced pressure from Westrom, and the GOP took notice. The National Republican Congressional Committee seized on Peterson’s travel expenses from car leases and his personal plane, and spent millions on attack ads to try to paint the conservative Democrat as out-of-touch.

Peterson, 70, played up his agricultural expertise and stewardship of the 2014 farm bill to shore up support.

Westrom, a 41-year-old attorney who has spent nearly two decades in the state Legislature, had called for new voices in Washington to break gridlock in Congress.