In every presidential election, many different causes are cited as tipping the scale in one direction or the other. There is certainly no shortage of reasons for President Obama’s re-election being bandied about.
One of the more interesting notions that has popped up in election post-mortems is that better-than-usual coverage of GOP-driven voter suppression was instrumental in energizing African and Latino Americans, and to some extent, even white moderates, as well as progressives. There are some interesting statistics to support the argument, although available data is not conclusive. For example, in “How the GOP’s War on Voting Backfired ,” The Nation’s Ari Berman explains,

Take a look at Ohio, where Ohio Republicans limited early voting hours as a way to decrease the African-American vote, which made up a majority of early voters in cities like Cleveland and Dayton. Early voting did fall relative to 2008 as a result of Ohio Secretary of State Jon Husted’s cutbacks in early voting days and hours, but the overall share of the black electorate increased from 11 percent in 2008 to 15 percent in 2012. More than anything else, that explains why Barack Obama once again carried the state…According to CBS News: “More African-Americans voted in Ohio, Virginia, North Carolina and Florida than in 2008.”
The same thing happened with the Latino vote, which increased as a share of the electorate (from 9 percent in 2008 to 10 percent in 2012) and broke even stronger for Obama than in 2008 (from 67-31 in 2008 to 71-27 in 2012, according to CNN exit polling). The share of the Latino vote increased in swing states like Nevada (up 4 percent), Florida (up 3 percent) and Colorado (up 1 percent). Increased turnout and increased support for Obama among Latinos exceeded the margin of victory for the president in these three swing states.
We’re still waiting on the data to confirm this theory, but a backlash against voter suppression laws could help explain why minority voter turnout increased in 2012. “That’s an extremely reasonable theory to be operating from,” says Matt Barreto, co-founder of Latino Decisions, a Latino-focused polling and research firm. “There were huge organizing efforts in the black, Hispanic and Asian community, more than there would’ve been, as a direct result of the voter suppression efforts.” Groups like the NAACP, National Council of La Raza, National Association of Latino Elected and Appointed Officials, and the Asian-American Legal Defense Fund worked overtime to make sure their constituencies knew their voting rights.
…Racial minorities made up 28 percent of the electorate in 2012, up from 26 percent in 2008, and voted 80 percent for Obama. “Romney matched the best performance among white voters ever for a Republican challenger–and yet he lost decisively in the Electoral College,” wrote Ron Brownstein of National Journal. Minorities also accounted for 45 percent of Obama’s total vote. That means that in the not-so-distant-future, a Democrat will be able to win the presidency without needing a majority of white votes in his or her own coalition. In a country with growing diversity, if one party is committed to expanding the right to vote and the other party is committed to restricting the right to vote, it’s not hard to figure out which one will ultimately be more successful.

Of course the reason for the increase in the share of the electorate held by people of color could be that lots of white voters did not cast ballots on election day because they liked neither Romney or Obama. We will need the final white turnout as a percentage of the eligible white voter figures, and then compare them to ’08 to make a credible guestimate.
Joy-Anne Reid adds at The Griot:

Florida’s reduced early voting period actually galvanized black churches, who took full advantage of the one remaining Sunday to conduct a two-day “souls to the polls” marathon. And even as Election Day turned into a late Election Night, and with the race in Ohio, and thus for the 270 votes needed to win the presidency, called by 11 p.m., black voters remained in line in Miami-Dade and Broward, two heavily Democratic counties in Florida, where black voters broke turnout records even compared to 2008…
“Republicans thought that they could suppress the vote, but these efforts actually motivated people to get registered and cast a ballot,” Ohio State Sen. Nina Turner said. “It’s no surprise that the communities targeted by these policies came out to the polls in a big way–they saw this not just as an affront to their rights, but as a call to action.”
“From the tours we did in 22 states, it became clear to us that many blacks that were apathetic and indifferent became outraged and energized when they realized that [Republicans] were changing the rules in the middle of the game, in terms of voter ID laws, ending ‘souls to the polls,'” said Rev. Al Sharpton, president of the National Action Network, who also hosts MSNBC’s Politics Nation. “So what was just another election, even though it dealt with the re-election of the first black president, took on a new dimension when they realized that they were implementing the disenfranchisement of black voters.”

Sharpton and NAN held “souls to the polls” rallies across Florida the weekend before Election Day, in a push dubbed “Operation Lemonade” because pastors and voters sought to turn the “lemons” Republicans created by cutting Florida’s early voting period down to six days, into “lemonade” by getting out the vote.
“I’m very happy that South Florida voters staved off the voter suppression from Gov Rick Scott and the Republican led House and Senate,” said Bishop Victor T. Curry, pastor of Miami’s New Birth Baptist church, and that city’s NAN chapter president, who led the “Operation Lemonade” effort in Miami-Dade county. “Democracy WON!”
“We did a rally in Eatonville,” Sharpton said. “And I had a guy come up to me and call voter ID a poll tax. He said to me, ‘I’m 85 years old, I don’t drive so I don’t have an ID and don’t need one. It costs me money to get one, and its 27 miles from my house so I have to get someone to drive me there.’ When I started putting people like this on the air (on his daily talk radio show) and bringing them up on stage at rallies, we saw the energy increase immediately as a result.”
The same could be said of Ohio, and in both states, the substantial early vote among African-Americans appears to have been decisive for Obama.
“If they had left it alone, I think they would not have seen the long lines at the polls,” Sharpton said. “I think what they did gave us the spark that we needed in this election.”

It’s likely we will never have a verifiable estimate of how many voters turned out primarily because they were angered by Republican voter suppression measures, particularly the ‘war on early voting.’ But it’s not hard to imagine that it galvanized a significant number of people.
CNN’s Roland Martin sheds some light on how African America voters were energized by Republican voter suppression:

Obstacles like these rekindled the feeling among many African-Americans of the tactics enacted during the civil rights movement to keep blacks from voting. So pastors, deacons and laymen pushed and prodded their members to cast absentee ballots, and pushed hard for their members to stand in lines that during the early voting period can last as long as eight hours.
In Ohio, activists hit the salons, barbershops, recreation centers and churches to rally voters to do their civic duty. Black radio stations were enlisted in the battle to protect the sanctity of the ballot.
Even when the networks were calling the election for President Obama on Tuesday, Florida residents were still standing in line to vote, some places in the rain, doing their part to push back.
According to NAACP president and CEO Ben Jealous, the organization registered 432,000 voters, a 350% increase over 2008

I suspect the long lines in Florida and Ohio pissed off a significant number of white voters, as well as voters of color, whose precincts were apparently targeted for long waits. It undoubtedly angered whites who had to wait in those lines. But it likely also turned off conscientious whites across the political spectrum who saw the lines on television. Most attentive voters likely noticed that Florida Governor Rick Scott and Ohio Secretary of State Jon Husted, both Republicans, were responsible.
Their repugnant efforts to restrict early voting and their dubious justifications provided one more late-breaking reason not to vote for Republicans. Rick Scott and Jon Husted made it embarrassing for at least some Republican moderates to see themselves as part of the same party that supports racially-motivated voter suppression.
It’s not so disappointing that Republican bomb-throwers, like Limbaugh, Hannity, Coulter, O’Reilly and other lightweights support voter suppression. We expect them to do so. But the GOP’s high tolerance for voter suppression is never discussed by even by the more genteel conservative commentators at the better newspapers and conservative magazines. They have been appallingly silent on the topic. Although commentator David Frum called the voting fiascos on election day “disgraceful,” for example, he dances around the racial discrimination that motivates it.
Another lesser-known Republican operative I saw on one of the political talk shows pooh poohed early voting suppression as ‘ridiculous,” as if it was a silly irrelevant problem, instead of an outrageous betrayal of America’s most important right. The higher-brow Republican commentators should be called out on the topic and compelled to address the morality of voter suppression. So far none of them has shown the courage of former Florida Governor Charlie Crist in standing up to his party and nailing it for its cowardly evasion of the issue.
It’s as if the Republican opinion leaders are tacitly admitting “Our ideas are so weak that the only way we can win is by restricting voting by people of color.” That’s a sad legacy for a party that once had leaders worthy of respect. For honest journalists, there’s no avoiding the fact that suppressing votes by African and Latino American citizens was a central element of Republican strategy in the 2012 elections.
In all, 36 percent of white men and 42 percent of white women voted for Obama, and those numbers are pretty low. To conclude on a hopeful note, however, twenty or even ten years ago, I doubt more than a third of white men would have been willing to vote for an African American presidential candidate. After President Obama completes his second term, it seems reasonable to hope that even more whites will oppose racial voter suppression in future elections.