ST. PAUL (AP) — Mark Dayton is campaign-tested, a liberal politician known in all corners of Minnesota. The Democratic gubernatorial nominee has plenty of money and proven appeal with older voters.

Republican Tom Emmer is the relative newcomer, a bedrock conservative with six years in the Legislature. He brings hockey-dad appeal and a simple small-government message that stands to be potent to people struggling through this rocky economy.

Both men have blemishes their governor’s race opponents are sure to exploit, from professional to personal lapses. And neither knows what to expect from Tom Horner, the former GOP strategist running as the Independence Party nominee.

What’s clear is the next 12 weeks will be a showcase in contrasts perhaps as stark as the state has seen.

“I don’t think you will find two major party nominees in a statewide race in this country this year with bigger ideological differences than Dayton and Emmer,” said Steven Schier, a Carleton College political science professor.

“The bases have spoken and they are very far apart from each other. And they are demanding the electorate choose one base philosophy or the other.”

The two main contenders diverge on almost everything. Dayton is pushing for a new upper income tax bracket; Emmer says taxes should be cut. Dayton favors legalizing gay marriage; Emmer wants a constitutional amendment prohibiting it.

Dayton, Emmer and Horner won their respective nominations in party primaries Tuesday. Dayton’s victory was clouded by a close finish and a concession from House Speaker Margaret Anderson Kelliher that didn’t come until lunchtime Wednesday.

The stakes are high: The winner will set the tone for dealing with a possible $6 billion budget deficit and will have a large say in setting new political boundaries following this year’s census, an exercise that will shape elections for a decade.

Republicans want to build off the eight years of GOP Gov. Tim Pawlenty, who is ramping up a possible presidential run. Democrats are eager to win the post after five straight losses dating to 1990.

Dayton has been in tough races before, with two wins and two losses to show for it. Ten years ago, he defeated a Republican senator in a campaign where he spent $12 million from a personal fortune.

His time in Washington was a disappointment, even to him. Dayton never acclimated to the slow-moving institution, he was panned as being aloof and ineffective and he took fire for temporarily closing his office in response to concerns over threats of terrorism. By 2005, he ruled out a re-election bid to return to Minnesota, where he began mulling a run for governor.

A Republican Party ad hitting the air Thursday refers to “erratic” behavior and calls Dayton “too risky for Minnesota.”

“I expected the smears to start right away and they have,” Dayton said after a Wednesday party unity rally at the Capitol.

Even in an atmosphere that favors outsiders, Dayton says his experience will matter to voters.

“You wouldn’t ask someone with no business experience to come in and be CEO of 3M or Target,” Dayton said during the primary campaign. “So why would people think that there isn’t a baseload experience in government leadership that’s essential in leading the ship of state?”

Emmer, though in the House minority for most of his tenure, made a name for himself with scalding speeches and provocative stances. He once advocated castration of sex offenders.

He entered the race a year ago and bolted past a better-known, better-financed opponent for the party endorsement. His insurgent message attracted the support of former Alaska Gov. Sarah Palin.

Emmer has tried to escape an image that he is from his party’s extreme right and said he wants the campaign to be about the economy, not social issues.

On Wednesday, Emmer said his opponents are taking the approach that when “government runs out of money, just go right back to hardworking men and women and their businesses and ask for more. We’re running on a different message.”

While the national political climate favors Republicans, Emmer has ground to make up after a summer of miscues. He spent 10 days trying to explain where he stood on the minimum wage — he once sought to abolish it — and he promoted a veterans initiative he actually voted against. Amid party insiders’ worry about his campaign, Emmer replaced his top staff last week.

Both Dayton and Emmer have had personal issues come up. Dayton disclosed past battles with depression and alcohol; Emmer’s opponents have hammered him over two drunken driving incidents and legislation he later authored to change DWI laws.

Then there’s Horner.

The co-founder of a Twin Cities public relations company is expected to figure in the November outcome. Jesse Ventura put the Independence Party on the electoral map when he was elected governor in 1998 back when the IP was known as the Reform Party.

Horner doesn’t have Ventura’s flair. He’s a wonk by nature. And he’s at a financial disadvantage, though he says he’ll start airing TV ads in a few weeks.

Horner comes from a Republican background but has advocated for tax increases as part of a budget solution, something that may resonate with center-left voters. He considers the Dayton-Emmer matchup ideal for his uphill candidacy.

“I’m the candidate who best has the ability to build a broad base,” Horner said. “It’s hard to see them building a base much beyond their political party.”