As Republican candidate Mitt Romney’s voluminous tax returns sink into the American psyche, some line items stand out for sheer size, most notably his contributions to the Mormon church.

According to his 2010 tax returns and 2011 estimate, the former Massachusetts governor donated a total of $4.13 million to The Church of Jesus Christ of Latter-day Saints over those years.

Tithing at a 10 percent level of income is required of observant Mormons. Church founder Joseph Smith wrote that members of the faith “shall observe this law, or they shall not be found worthy to abide among you.”

A slew of poll results over the past year, from Gallup and the Pew Center to CNN and ABC, have all shown that Americans’ attitudes toward Mr. Romney’s Mormon faith may play a decisive role in his campaign.

Now that the strength of his religious conviction has a dollar sign attached to it, the question arises: Will his tithing invigorate the uneasiness that many Americans, including evangelicals and some other Protestants, have toward the Mormon church and its adherents?

Some evangelicals who question the legitimacy of the religion, doubting its Christian credentials, may warm to Romney’s generosity, says Michele Dillon, sociology professor at the University of New Hampshire in Durham. Others, she adds by e-mail, “especially some who are already highly skeptical of Mormonism, will probably use his generous tithing as further evidence that Mormons, in these voters' minds, are too much in the clutches of their church, and who knows what he might do to advance some alleged ‘Mormon agenda’ if elected?"

The eye-popping number may be just the push that the issue needs to move to center stage in Romney’s campaign, says presidential historian Charles Dunn.

“Romney needs to tackle this issue head-on,” says the author of “The Presidency in the 21st Century.” He likens this moment for the candidate to the question that faced John F. Kennedy in the 1960 presidential race when Baptists and other Protestant groups questioned whether his Catholic faith would divide his loyalties.

Kennedy opted to take the discussion directly to the Southern Baptists, speaking at their convention.

“He addressed them directly and told them that he was an American first,” says Professor Dunn, adding that the Democratic candidate made it clear that he would not allow the Vatican to make US policy. “Romney needs to have the equivalent of this moment for JFK,” he says, if for no other reason than to make clear that as the US Constitution says, “there shall be no religious qualification for office.”

Candidate Romney addressed the topic in his previous presidential run back in 2007, saying, “I believe in my Mormon faith and I endeavor to live by it,” even directly tackling the doctrinal question that some evangelical groups have raised, suggesting that Mormonism is not Christian.

“There’s one fundamental question about which I’m often asked,” he said, “What do I believe about Jesus Christ? I believe that Jesus Christ is the son of God and the savior of mankind.”

But questions of doctrine may always drive the issue for a sector of the population, says Jeffrey Berry, professor of political science at Tufts University in Medford, Mass.

“Mormonism could still emerge as a problem for Romney amongst a small group of Americans who are prejudiced against its teachings,” he says. However the most damaging information arising from the newly released tax reforms for a wider swathe of Americans he suggests, may relate more to offshore tax havens and foreign bank accounts.

Even if the level of Romney’s tithing pushes the issue of his faith into the spotlight, the level and length of his generosity may actually help broaden his appeal among many who might not otherwise relate to Mormon practices.

The practice of tithing is not unique to the Mormon church, points out Villanova University political science professor Catherine Wilson.