In a recent article, “The GOP War on Voting,” I examined how GOP officials have passed laws in a dozen states since the 2010 election designed to impede traditionally Democratic voters at every step of the electoral process, which could prevent millions of students, minorities, legal immigrants, ex-convicts and the elderly from casting ballots in 2012.

Here’s the summary:

Kansas and Alabama now require would-be voters to provide proof of citizenship before registering. Florida and Texas made it harder for groups like the League of Women Voters to register new voters. Maine repealed Election Day voter registration, which had been on the books since 1973. Five states—Florida, Georgia, Ohio, Tennessee and West Virginia—cut short their early voting periods. Florida and Iowa barred all ex-felons from the polls, disenfranchising thousands of previously eligible voters. And six states controlled by Republican governors and legislatures—Alabama, Kansas, South Carolina, Tennessee, Texas and Wisconsin—will require voters to produce a government-issued ID before casting ballots. More than 10 percent of U.S. citizens lack such identification, and the numbers are even higher among constituencies that traditionally lean Democratic—including 18 percent of young voters and 25 percent of African-Americans.

Now, thanks to a new report from the Brennan Center for Justice at NYU, we have the best estimate yet for just how many voters will be impacted: “these new laws could make it significantly harder for more than five million eligible voters to cast ballots in 2012,” the report states (emphasis added).

According to the report, “states that have already cut back on voting rights will provide 171 electoral votes in 2012–63 percent of the 270 needed to win the presidency.” It just so happens that of the twelve most competitive swing states in the country, “five [Florida, Georgia, Iowa, Nevada and Ohio] have already cut back on voting rights.”

The Brennan Center notes that “these new restrictions fall most heavily on young, minority and low-income voters, as well as on voters with disabilities”—in other words, those most likely to vote against the GOP.

Here’s how the Brennan Center calculated the number of voters adversely impacted by the new laws:

(1) New photo ID laws for voting will be in effect for the 2012 election in five states (Kansas, South Carolina, Tennessee, Texas, Wisconsin), which have a combined citizen voting age population of just under 29 million. 3.2 million (10.3%) of those potential voters do not have state-issued photo ID.

(2) New proof of citizenship laws will be in effect in three states (Alabama, Kansas, Tennessee), two of which will also have new photo ID laws. Assuming conservatively that those without proof of citizenship overlap substantially with those without state-issued photo ID, we excluded those two states. The citizen voting age population in the remaining state (Alabama) is 3.43 million. Of those potential voters, 240,000 (7%) do not have documentary proof of citizenship.

(3) Two states (Florida and Texas) passed laws restricting voter registration drives, causing all or most of those drives to stop. In 2008, 2.13 million voters registered in Florida and, very conservatively, at least 8.24% or 176,000 of them did so through drives. At least 501,000 voters registered in Texas, and at least 5.13% or 26,000 of them did so via drives.

(4) Maine abolished Election Day registration. In 2008, 60,000 Maine citizens registered and voted on Election Day.

(5) The early voting period was cut by half or more in three states (Florida, Georgia and Ohio). In 2008, nearly 8 million Americans voted early in these states. An estimated 1 to 2 million voted on days eliminated by these new laws.

(6) Two states (Florida and Iowa) made it substantially more difficult or impossible for people with past felony convictions to get their voting rights restored. Up to one million people in Florida could have benefited from the prior practice; based on the rates of restoration in Florida under the prior policy, 100,000 citizens likely would have gotten their rights restored by 2012.

It’s important to put these numbers in perspective. Again and again, GOP lawmakers point to voter fraud as the reason for these new laws, even though study after study, investigation after investigation, has found that voter fraud is a minuscule problem in American elections. A major probe by the Bush Justice Department between 2002 and 2007, for example, failed to prosecute a single person for going to the polls and impersonating an eligible voter. Of the 300 million votes cast in that period, federal prosecutors convicted only eighty-six people for voter fraud. A much-hyped investigation in Wisconsin, meanwhile, led to the prosecution of only .0007 percent of the local electorate for alleged voter fraud.

So essentially, based on a handful of suspicious incidents, 5 million eligible voters could be disenfranchised in 2012.