(RNS) Making up half of Republican primary voters, evangelicals appear to be turning out to support Rick Santorum's resurgent campaign in record numbers and are increasingly influencing the shape of the party.

Former Pennsylvania Sen. Rick Santorum has broad appeal among some evangelical voters because his conservative Catholic views dovetail with their social concerns. RNS photo courtesy Gage Skidmore.

Perhaps just as important, conservative Christians are increasing their crucial financial support and volunteer hours as Santorum tries to keep his momentum heading into Tuesday's (March 20) Illinois primary.

According to the Faith and Freedom Coalition, headed by longtime evangelical political activist Ralph Reed, evangelical Christians account for just over 50 percent of the turnout so far in the Republican primaries, the highest rate ever and a significant increase over the 44 percent evangelical voting rate in 2008.

Moreover, Santorum has won a third of those votes, compared to Mitt Romney's 29.74 percent and Newt Gingrich's 29.65 percent.

Faith and Freedom based its analysis on the entrance and exit polling data from 16 primaries and caucuses. The data show that some 4.29 million evangelical Christian voters have cast ballots so far -- or 50.53 percent of the 8.49 million total votes cast.

Reed said the turnout is up across the board, and not just in the South, where conservative Christians helped deliver a two-state primary sweep of Alabama and Mississippi to Santorum last Tuesday.

"Conservative people of faith are playing a larger role in shaping the contours and affecting the trajectory of the Republican presidential nomination contest than at any time since they began pouring out of the pews and into the precincts in the late 1970s," Reed said.

They are also putting their money where their values are.

Santorum is collecting nearly half of his donations from donors who gave less than $200, according to an analysis of Federal Election Commission filings by the Campaign Finance Institute -- a higher percentage than any of his Republican rivals.

And while Santorum has trailed his rivals in overall fundraising, he may be catching up fast. Politico reported that Santorum raised $9 million in February compared to Romney's $11.5 million, Santorum's best month yet.

Santorum's campaign also said that in the wake of Southern primary victories, Santorum raised $1 million over a 24-hour period through a grass-roots "money bomb" drive. That is in addition to some $1.8 million pledged by wealthy conservatives, many of them evangelical Christians, at a Santorum fundraiser on March 9 in Houston.

The Susan B. Anthony List also announced on Thursday that it would move its bus tour and mobilization effort for Santorum to Illinois -- the kind of "on the ground" efforts that have brought Christian conservatives out for Santorum and upended the predictions of polls and pundits.

"I think there has been a long-term political impact beyond the endorsements" of big-name Christian leaders, said John Green, an expert on religious voting patterns at the University of Akron in Ohio.

Green likened the evangelical support for Santorum to black voters in the 2008 Democratic primaries, who initially backed Hillary Clinton but coalesced around President Obama once he took Iowa and got on a roll.

"There is a pent-up demand for a certain kind of candidate, but that candidate has to demonstrate that they can win," said Green. Big endorsements, he said, act as a kind of "pump primer" to get voters -- in Santorum's case, Christian conservatives -- ready to jump on board.

Whether that can carry Santorum to a win in Illinois on Tuesday is uncertain. The former Pennsylvania senator is close behind Romney in most polls, and Illinois' downstate Republicans tend to be conservative Christians like those in the deep South.

Ironically, Santorum would get a huge boost by doing something he has not yet done: win the votes of his fellow Catholics. Santorum is often mistaken for an evangelical by GOP voters; a recent Pew Forum survey showed that among Republican and Republican-leaning voters, just 42 percent of Catholics know that Santorum is himself Catholic.

But as James Warren wrote in The Atlantic, Santorum graduated from a Catholic high school in Illinois, Carmel High School outside Chicago. That could give him a leg up in Obama's home state, and a critical win over Mitt Romney.

"A Santorum victory in Obamaland next week would be stunning -- but it wouldn't necessarily be a surprise," Warren said.