President Obama’s decision to announce his “personal” support for same-sex “marriage” came after more than three and one-half years of his “evolution” on the issue and three days after his vice president – seemingly unintentionally – so boxed him in with his confessional-style comments that he had no other option.

Those professing same-sex affinity or advocating for its complete cultural and legal acceptability have great influence in the Obama administration; according to Politico, “It’s hard to find a person in Obama’s orbit who didn’t have a relationship with gay-rights advocates or the highly influential community of gay and lesbian donors who have supported the president”.

Yet apart from the behind-the-scenes political machinations, or the profound and troubling policy implications of the president’s decision, the decision itself could well determine the outcome of the fall election. That’s not hyperbole, but Electoral College math written as large as it can be.

Considering that ten of the sixteen key battleground states have marriage amendments that could be overturned by the President's new policy position on marriage, his announcement almost ensures that marriage will again be a major issue in the presidential election.

The critical swing states of Ohio, Colorado, Virginia, Florida, and North Carolina, and possibly Pennsylvania, are now much more likely to be won by Mitt Romney in November. Why?

Realizing the centrality of marriage to the well-being of children, the vibrancy of the economy, and the very nature of our culture, social conservatives are as passionate about preserving marriage as the West and East Coast cultural elites are about changing it – and there are a lot more of us between the two coasts.

Yes, the cultural elites and homosexual activists are wealthy and give generously to candidates and ballot initiatives sympathetic to their priorities. Their influence within the Democratic Party and its candidates is pronounced, however, they constitute a relatively small number of voters.

Additionally, there are three other factors that must be considered in any political calculus:

Social conservatives, especially those animated by their faith and the moral imperative of raising their children according to the tenants of their faith, will run to and not from this assault on marriage and family.

In politics, numbers matter – and in sheer volume, Evangelicals, traditional Catholics, and rural voters that place a priority on the teachings of their faith far outdistance the cultural elites who advocate for the redefinition of marriage.

Secondly, the support of the African American community is essential to Mr. Obama’s reelection – and that support has now substantially vitiated.

Even left-of-center CNN commentator Roland Martin, who is black, said he has spoken with a number of what he called “liberal” pastors who characterized the president’s actions as “shameful” and “pitiful.” He noted that the lack of enthusiasm for Mr. Obama among African Americans, due to specifically to his move on same-sex “marriage,” could well determine who next occupies the Oval Office. We’ve heard the same messages from African-American and Hispanic pastors in the days since the president drew his line in the cultural sand.

Keep in mind that margins of victory can be very thin.

In 2004, our mutual native state of Ohio gave its 20 electoral votes – and, thus, the presidency – to Mr. Bush by slightly over two percent of the popular vote. This narrow victory was fueled in large part by President Bush doubling his support among African American voters in the state because of the Ohio marriage amendment.

If socially conservative voters, energized by the need to defend marriage, turn out in large numbers, and even 10-15 percent of black voters stay home – voters who otherwise would have supported Mr. Obama – due to his pronouncement on homosexual “marriage,” the election goes to Mitt Romney.

Or, for that matter, if the historically modest African American support for the GOP nominee grows to, say 15 percent, again, the advantage goes to the Romney ticket.

Lastly, in the 32 states where voters have been allowed to express their views, all 32 have affirmed traditional marriage and rejected its same-sex redefinition. Even in liberal California, Prop. 8 won by only 600,000 votes in 2008 – with President Obama at the top of the Democratic ticket and carrying the state for his election.

Earlier this month, more than three-fifths of North Carolina’s voters affirmed the historic definition of marriage as being between one man and one woman. This fall, voters in Minnesota, Maryland, Maine, and Washington state are expected to vote on marriage.

Rest assured that the president’s decision to walk down the isle of same-sex marriage will be met by voters who will not hold their peace, but will speak loudly at the ballot box. His “personal” shift on the matter could well be determinative not only of these votes but of his continued residence at 1600 Pennsylvania Avenue.

Tony Perkins is president of the Family Research Council. Ken Blackwell is senior fellow for family empowerment at the Family Research Council and former Ohio secretary of state.