In the last 50 years, Catholics have for the most part voted Democratic. In 2008, Barack Obama won their vote. In 2000, Al Gore was victorious. Ronald Reagan and George W. Bush were exceptions. But some Pundits say the Ryan pick could give Romney the edge,
"I think the selection of Paul Ryan definitely energizes more Catholic voters than it disappoints," says Deal Hudson, the former Catholic outreach director for the Republican National Committee between 2000 and 2004. "They are going to respond well to his pro life, pro marriage positions."
Hudson contends Ryan's Catholic appeal, however, will rely heavily on whether the social justice or pro-life Catholics get the microphone. [Opinion: Paul Ryan's Radical Budget Views.]
"There is going to be a battle of whose opinion of Ryan gets the most coverage," Hudson says. "[Ryan] represents a generation of Pope John Paul II Catholics as opposed to the old Catholics of assimilation represented by Joe Biden."
And the Catholic church doesn't shy away from the political spotlight.
When Ryan defended his budget plan under the guise it was based off of his understanding of Catholicism, Jesuit leaders at Georgetown University cried foul. And the U.S. Conference of Catholic Bishops wrote Ryan in protest.
Already, Sister Simone Campbell, the executive director of Network, a Catholic social justice lobby, is "gunning for Ryan." Campbell launched a nationwide bus tour this summer spreading the word about Ryan's budget, which she says is immoral and ignores Catholic social teachings.
"I don't understand why Mitt Romney picked Paul Ryan," Campbell says. "I met with him in July, and he is all about the numbers in his head, but we are talking the real world and real people."
Campbell, who has invited Romney and Ryan to join her for a day of service, urges Catholics to cast ballots not based on pro-life issues, but on social teachings above all.
"The life issue separates Catholics, but so does having food for children to eat and having healthcare so people don't die unnecessarily," Campbell says.
But there is another political war raging within the church that could play well for Ryan.
When the president announced earlier this year that religious institutions' healthcare plans were required to offer birth control to employees, diocese across the country spoke out. In May, 43 Catholic institutions from universities like Notre Dame and other social service groups filed lawsuits against the Obama administration over the rule. [See a collection of political cartoons on the budget and deficit.]
And just like leadership is diverse, so is the Catholic constituency.
Catholics account for nearly one in four voters in this country and in a May Gallup poll, Catholic voters were "evenly split" between Obama and Romney with white Catholics favoring Romney by nearly twenty points and Hispanic Catholics opting for Obama by 50.
No doubt both presidential campaigns will be battling it out for the key constituency, but Catholics are not a monolithic group. Mass-attending Catholics tend to vote more conservatively than less religious Catholics, and ethnicity reveals a major political schism within the church.
John Gehring, the Catholic programs director for Faith In Public Life Action Fund, argues that while Romney was leading among some Catholics earlier this year, a Ryan pick hurt his chances with the swing voters.
"Catholics are steeped in a tradition that puts the common good and community before extreme individualism," Gehring says. "This is going to be a factor with quite a few moderate Catholic voters in key states where Ryan's appeals to the wonders of the free market are going to ring hollow."
Catholics make up a third of the population in critical swing states like Wisconsin, Michigan, Ohio and Pennsylvania.
Gehring says if Ryan wanted to help Romney with the Catholic vote, he would stop reminding people his budget was based off of his understanding of Catholic teachings.
"Ryan wants to have this debate on Catholic terms and I am not sure why," Gehring says. "He has been told he is getting it wrong. Catholics are not buying what he is selling."