Several seats changed hands, and winning candidates on both sides offered similar explanations.
"Minnesota was on fire last night," a leading national blogger on the political left exulted Wednesday morning, scanning the surprises that voters had wrought the night before.
And Dakota County played a huge role in that blaze.
A county whose blue tinge had been all but wiped out in the Republican wave of 2010 suddenly was streaked with blue again all across its northern reaches, from Burnsville and Eagan clear over to the Washington County border.
Six of the 11 House seats and four of the six Senate seats that touch the county wound up in the hands of Democrats.
"It was a tough, tough situation," said veteran Hastings Republican Denny McNamara, who survived the conflagration. "A lot of really good candidates worked hard but had tough races."
"I don't know if I'd pin it on any one thing," he said. "The pendulum of politics just swings, and it never swings to the middle -- it goes too far every time."
Up to a point, winning candidates on both sides agreed on some of the ingredients in the shift:
• The two constitutional amendments on the ballot energized folks on both sides, but in Dakota County arguably more on the liberal side.
"I believe the amendments ended up helping Democrats," said Laurie Halverson, a DFLer who claimed a House seat in Eagan as a first-timer. "Anecdotally, in the last few weeks a number of people asked me how I was voting on the amendments, and when I said 'no' to both, they would say, 'I'm voting for YOU.' Some of them were casting those votes for people they knew in their own lives."
Dakota County voted 54 percent "no" on the amendment to ban gay marriage.
• Turnout rose on the left after a glum year in 2010.
"The Obama wave was the most important thing," McNamara said, after a 2010 that featured intense Tea Party activism.
Second District Congressman John Kline won 56 percent in Dakota County in 2008, during the first big Obama Wave election. He captured 61.3 percent in 2010. But, partly because redistricting altered his borders, he sank to 52.4 percent in Dakota County on this Election Day.
• The DFL brand benefitted from the presence at the top of the ticket of a widely popular senator who's seen as a moderate and a listener.
"She is an unbelievably gifted politician," Republican McNamara said. "I've seen her speaking at a banquet to a group of sportsmen, not usually a big DFL group, and have them just eating out of her hand as she describes how she helped delist the grey wolf. It makes it tough to switch over when the top two clicks on your ballot have been Democrats."
Although her opponent, Kurt Bills, is a Dakota County guy -- between him and former Gov. Tim Pawlenty of Eagan, the county has been a fountain of statewide GOP aspirants -- Klobuchar won 62 percent in the county, far better than Obama's 51 percent. Klobuchar even beat Bills in his own hometown, winning six of seven precincts in Rosemount. She carried the city 53.6 percent to 46.4 percent even as Romney was winning there 52-48, and the city chose a new GOP state representative to replace Bills in the Legislature.
• Within Minnesota, meanwhile, the GOP brand got tarnished over the past couple of years, notably in the Legislature, where a sex scandal involving a top female lawmaker and a male aide is still reverberating.
But it wasn't just those kinds of headlines, DFLers said. It was also on-the-ground realities.
"What I heard from people on the doorstep is that schools that serve my district are in difficult times," due in part to state financial support or the lack thereof, said Will Morgan, a Burnsville DFLer who reclaimed a seat he lost two years ago.
"Districts like Lakeville and Burnsville," he added, "are looking at huge class sizes, four-day weeks, school closings. No one would think suburban schools would face these kinds of problems. We've got to get a handle on this."
But that kind of talk alarms some conservatives.
"We're very concerned about potential tax increases falling on the business community," said Todd Bornhauser, executive director of the Lakeville Area Chamber of Commerce.
"If the DFL is interested in reinstating LGA [local government aid] or the market homestead credit or enacting large increases in funding education, where are those dollars going to come from? In the past, a large amount of DFL tax increases fell directly onto the business community. And this time there are no checks and balances -- it's all DFL, both houses of the Legislature and the governor. Whatever their agenda is, they can move forward with it."
At the lunch hour on Wednesday, hours after results came in, Bornhauser shot an e-mail out to his members that began: "I am still in shock from last night's results, and I am very concerned for my members and the business community!"
He invited folks to a session that very afternoon devoted to "dissect[ing] what the election means for advancing the priorities of the statewide business community at the 2013 Legislature."
Hearing of that session, DFLer Morgan said: "My door is open if people are concerned. Come talk to me. I served four years in the Legislature before and had very good relations with the president of the Burnsville chamber.
"You know, we are in this together. We live in the same community, drive the same streets, our kids are in the same schools. We've got to talk. That's part of the problem. Pick up the phone and let's talk."
Staff writer Dylan Belden also contributed to this article. David Peterson • 952-746-3285