Congressional Democrats are warning that stricter voter identification laws sweeping through state legislatures could suppress voters in the 2012 elections.

At least 34 states have introduced legislation, with varying degrees of restrictiveness, that would require voters to display identification at the polls before they are given a ballot. Some of these laws require voters to produce photo identification; some do not.

The battleground state of Wisconsin has a new law requiring photo IDs, while proposals at various legislative stages in the perennial presidential swing states of Ohio and Pennsylvania are also giving Democrats heartburn. The more restrictive voting ID measure in Ohio is pending Senate floor consideration. A bill to introduce ID rules for the first time in Pennsylvania has passed the state House and is currently in a state Senate committee. Democratic National Committee spokesman Alec Gerlach said Ohio is “one of the states where this has been a big concern.”

A report by the Brennan Center for Justice, a public policy and law institute based at the New York University School of Law, found that more voter ID bills have been introduced this year than in any other year in history.

New voter ID laws have been enacted in Kansas and Rhode Island, and lawmakers in Alabama, South Carolina, Tennessee and Texas have moved to tighten laws previously in place, according to data collected by the National Conference of State Legislatures.

“When you have millions potentially unable to vote, it will undoubtedly have political consequences,” said Wendy Weiser, a co-author of the Brennan Center report.

Civil rights icon Rep. John Lewis (D-Ga.) called the laws a “poll tax” on the House floor. Sen. Michael Bennet (D-
Colo.) this summer asked the Department of Justice to review the voter ID changes to ensure that voting rights are not infringed on, writing in a letter that the measures “have the potential to block millions of eligible American voters.”

This week, Bennet said he hopes the DOJ will make sure the new laws do not disenfranchise voters or violate civil rights.

“The right to vote is the central foundation of our representative democracy. Some new state laws may impede the exercising of that right by thousands of Americans,” he said.

Fifteen Democratic Senators have joined Bennet’s effort. Democrats opposing voter ID laws say they unfairly target minorities, college students and the elderly — voters who are less likely to have a government-issued ID and people who, incidentally, traditionally vote for Democrats.

One estimate suggests that as many as 5 million voters could be affected by the rule changes in 2012 — a number greater than the margin of victory in the 2000 and 2004 presidential elections.

Democrats are reluctant to openly acknowledge the political consequences of these laws in future elections, saying the issue for them is about infringements on voter’s rights. But they do argue that the laws hurt Democratic voters more than Republicans.

Republicans counter that voter identification laws are essential to prevent voter fraud.

Wisconsin Gov. Scott Walker (R) said he is supporting voter ID legislation to make sure “elections are run fairly and securely.”

One sliver of good news for Democrats is that so far this year, voter ID bills have had little success in most of the states that President Barack Obama won in 2008 that will again be competitive in 2012.

Bills in Nevada, New Hampshire, New Mexico, Iowa and North Carolina have stalled, failed or were vetoed by the governor. Colorado, Florida, Virginia and Michigan already had voter ID laws in place and have seen no further tightening of the rules this year.

Weiser said the lack of success this year for voter ID bills in battleground states has more to do with split party control than the states’ statuses during national elections. The parties share power in Virginia, Colorado, Iowa, New Hampshire, North Carolina, Nevada and New Mexico. Still, she said, “The battleground states are the ones where the fights are the fiercest.”

The DNC’s Gerlach said winning small battles in these states is little conciliation when it comes to protecting voters.

“Even if it happens in a couple states, regardless of what states they are, it is not good,” he said.