Hoping to boost what they view as flagging confidence in the state's election system, Senate Republicans approved a bill on Thursday that would require Minnesotans to present photo ID at the polls.

The measure passed on a 37-26 party-line vote after two hours of debate. It would impose new identification requirements, eliminate vouching for most Election Day registrants and create new provisional ballots for voters whose eligibility is challenged.

Minnesota law does not require voters to present ID to vote if they have already registered. Under the bill, people without an authorized ID could obtain a free voter identification card after proving their citizenship and providing a "photographic identity document."

Sen. Warren Limmer, R-Maple Grove, the bill's sponsor, said the legislation would "bring integrity back to the state election system."

DFL senators said the new provisions would create significant obstacles for seniors, blacks and college students -- groups less likely to have an authorized ID.

"I believe [the bill] sets the state back," said Sen. Katie Sieben, DFL-Newport. "Sets the state back to the days of poll taxes and denying the right to vote to certain Minnesotans."

The vote echoes similar efforts moving through GOP-controlled state legislatures across the country, with opponents characterizing the efforts as voter suppression. Nine states require voters to present photo ID to vote.

Anticipating a possible veto from Gov. Mark Dayton, legislators have introduced a separate constitutional amendment proposal that would let voters decide the photo ID question in the 2012 election.

Dayton hasn't said outright that he will veto, but he has called the bill a "solution in search of a problem." A Citizens for Election Integrity study concluded that just 38 people -- all felons -- were convicted of voting or registering illegally in Minnesota in 2008.

Limmer said the bill's intent is modernization.

"I never ... justified this bill as a result of problems in the state, aside from the fact that we need to modernize," Limmer said. "The people of Minnesota deserve a system that is safe, secure and has the integrity expectation that every voter would want in the state of Minnesota."

But later, noting that 23,000 Election Day registration postcards were returned undeliverable in 2008, Limmer said Minnesota has "a big problem" that his bill addresses.

Opposing groups, like Common Cause Minnesota, say undeliverable postcards are not proof of voter fraud, since they can be returned for a variety of reasons.

"We are attempting to make sure that things like vouching for others doesn't result in fraud and those kinds of issues," said Sen. Dave Thompson, R-Lakeville.

State analysts estimate that about 144,000 eligible voters in Minnesota lack a valid, state-issued identification card. Still others may have identification that lists an old address outside the precinct, which would be invalid for voting purposes under the bill.

A facility administrator could vouch for senior citizens and other people in transitional housing wishing to register. Those voters would still have to present a photo ID listing their old address.

If a voter cannot produce sufficient ID or someone challenges his or her eligibility, he or she would have to cast a provisional ballot. That ballot would not be counted unless the voter could prove eligibility to the county auditor or municipal clerk within seven days.

"This bill's not about integrity," said Sen. Tom Bakk, DFL-Cook. "This bill is about putting roadblocks up to the ballot box."

Eric Roper • 651-222-1210