WASHINGTON, D.C. -- In what the polls show is a close race, both President Barack Obama and Gov. Mitt Romney are trying to win the Catholic vote.

But a new survey of America's religious voters shows that even within that group, voters base their decisions on very different issues.

The survey finds that even though many Catholics are pro-life, other issues may be more important to them at the polls.

Dr. Robert Jones helped put together a new national survey just released by the Brookings Institution in Washington. The survey had Catholics choose which issue they'd rather have their church deal with: social justice or right-to-life.

What can voters expect from the presidential campaign as they enter into the homestretch before Election Day? CBN News Political Editor John Waage has more.

"By a margin of two-to-one, that is 60 percent of Catholics, said that they felt the Church should put more emphasis on social justice and obligations to take care of the poor, even if it meant less emphasis on abortion and right-to-life," Jones said. "Thirty-one percent said the opposite." 

That indicates there may be no automatic big right-to-life vote coming from Catholics. And social justice Catholics are far more likely to be Obama voters.

Both Romney and Obama have many religious supporters, but they look very different from each other. Romney has the support of more white Christians. Obama has the support of more minority Christians.

"Romney has three-quarters of his coalition made up of white Christians," Jones said. "Obama, on the other hand, has less than four in 10 white Christians and has many more minority Christians in his coalition."

One significant finding: Jones told CBN News the number of religiously unaffiliated Americans has more than doubled since the 1990s, from seven percent to 19 percent of the population.

"They have now become as big, for example, as white evangelical voters in the American electorate. And they lean heavily Democratic while white evangelical Protestant Christians lean heavily Republican," Jones told us.

It's a surging coalition for the Democrats. The good news for Republicans is that these unaffiliated tend to vote in much smaller numbers.