MINNEAPOLIS — President Barack Obama won Minnesota Tuesday on his way to re-election, keeping alive the state’s long streak of backing Democrats for president and joining a popular Democratic U.S. senator in the victory column. Meanwhile, proposed constitutional amendments to ban gay marriage and require photo ID in future elections trailed in partial returns.

Though a late poll suggested the presidential race in Minnesota was tightening, the state’s voters did what they always seem to do: They chose the Democrat, giving Obama Minnesota’s 10 electoral votes.

No Republican has taken the state since Richard Nixon in 1972.

Sen. Amy Klobuchar beat Republican challenger Kurt Bills in a race called soon after the polls closed. Klobuchar, with big advantages in name ID and money, was a heavy favorite over Bills, a first-term state legislator who struggled for attention, money and voter support.

Two U.S. House members were locked in tight races. First-term GOP Rep. Chip Cravaack faced the strongest challenge, battling former Rep. Rick Nolan in northern Minnesota in a seat Democrats were anxious to flip. Rep. Michele Bachmann was running close with Democratic businessman Jim Graves in her bid for a fourth term.

Votes from the 8th traditionally trickle in slowly, but fears of an extra delay evaporated in a Duluth legislative district with two registered write-in candidates. St. Louis County Auditor Donald Dicklich said hand-counting there went smoothly.

A preliminary exit poll conducted in Minnesota for The Associated Press found economic worries outpacing health care reform, foreign policy and the federal budget deficit as state voters’ main concern. About six in 10 Minnesota voters said the economy is the most important issue facing the country — three times more than any other issue.

“The last four years have been crap,” said Marvin Grover Cleveland, 73, of Roseville, who voted for Romney. “It’s the economy. It went downhill. The debt has gone up so far. … Let’s try something else.”

Rene Maas, an over-50-year-old business analyst from Plymouth, voted for Obama, saying he needs more time.

“I think he’s made great strides and he’s really trying to get us moving in the right direction. It’s not going to be an instant change,” she said. “You can’t recover an economy fast. It’s going to take a while. It took a while to get into the mess.”

While interest in the race between Obama and Republican Mitt Romney was high, it was outstripped in intensity by the campaigns for and against the amendments.

Opponents of the marriage amendment outraised supporters by about two-to-one. But backers had history on their side: No gay marriage ban had ever been defeated at the hands of any state’s voters.

Photo ID requirements for voters are spreading through the country, but only Mississippi had one enacted through a constitutional amendment process.

Dale Charboneau, 66, a self-employed designer and artist in Roseville who said he was an independent, voted for Obama and against the gay marriage ban. But Charboneau supported photo ID, recalling the state’s close 2010 governor’s race and allegations of fraud.

“It’s a small percentage, but in an election like this, it could be enough to change it,” Charboneau said.

Terri Montbriand, 53, a medical secretary in Bloomington, followed the same path: for Obama, against the gay marriage ban, and for photo ID.

“I guess I didn’t think it was difficult to have to show an ID,” Montbriand said.

Minnesota historically ranks among the nation’s leaders in participation, and Secretary of State Mark Ritchie projected 3 million voters — a number that would approach 80 percent of eligible voters.

Voters also were deciding who would control the Legislature, with Democrats and Republicans in a district-by-district tug for House and Senate majorities. Republicans control both chambers, but Democrats hoped they could retake control they lost two years before.

The outcome has powerful implications for the policy agenda of Democratic Gov. Mark Dayton, who is halfway through a term already beset by a government shutdown after Republicans refused his call for higher taxes on the wealthy.