Civil war hasn't been easy on the Republican Party of Iowa.

For years, tensions have simmered between the party's centrist old guard and its Christian conservative wing. When four-term governor Terry Branstad left the executive mansion in January 1999, the door closed on 30 solid years of GOP control in the Hawkeye State. A slow trickle of seats away from the Republican majorities in the state House and Senate turned into a tidal wave in 2006. As the governorship, the congressional delegation and the state houses flipped into Democratic hands, grumbling over the scattered organization and stale messaging of Iowa's ruling GOP moderates crescendoed.

"They didn't want to fight," said Steve Scheffler, the president of Iowa's most prominent Christian group and a leading voice in the party's evangelical wing. "We want to fight the Democrats and expose them for the liberal left agenda that they hold."

At their convention in July, Iowa Republicans experienced their own change election. Backed by frustrated state Republicans and loyalists within his Iowa Christian Alliance, Scheffler ousted incumbent national committeeman Steve Roberts, a gravel-voiced 20-year veteran of Iowa's RNC delegation. Scheffler ally Kim Lehman of the Iowa Right to Life Committee won a corresponding slot as national committeewoman.

"The people who were running the Christian Alliance wanted to take power," the defeated Roberts told NBC/National Journal. "They wanted to take the whole enchilada. And they had the organization and the ability to do it."

Members of both factions acknowledge that Christian Alliance's convention victories were no sudden coup, but merely an exclamation point at the end of evangelicals' decades-long rise to prominence in the state that famously saw a groundswell of support for Southern Baptist minister Mike Huckabee during the January caucuses. But the warring sides differ sharply over what Scheffler's dominance will mean for party centrists and even those Republicans who agree with the Christian Right on social issues but would prefer not to speak too stridently on abortion and gay marriage.

Republicans, perhaps, like John McCain.

"It's awful timing for the McCain people," said political columnist David Yepsen of the Des Moines Register. Yepsen notes that, although Scheffler and Lehman are McCain supporters, rank-and-file social conservatives in the state have always been suspicious of McCain's relative lack of enthusiasm for pro-life homilies and "defense of marriage" legislation. McCain's challenge in Iowa will be to bring together moderates and evangelical hardliners -- bridging precisely those fault lines recently exacerbated by the party's reorientation.

Iowa Rep. Steve King, one of Congress' most staunchly conservative members, said that McCain's nomination may have actually widened that chasm. King -- who derided McCain's immigration plan during the Iowa caucuses but now says that he wholeheartedly supports his party's nominee -- believes that the Arizona senator's reputation as a maverick emboldened the party's more moderate faction. As soon as McCain's nomination gelled, "moderates that didn't have the clout to move the party in their direction would feel empowered by McCain's presumptive nomination," King said. "They [started] to flex their muscles a little bit."

Nevertheless, Scheffler ultimately won the party arm-wrestling match in July, by a vote of 788 to 543. Part of his platform was a promise of greater discipline among elected Republicans. Citing last-minute GOP defections from an anti-gay-marriage measure that stalled in the state House even during a period of GOP dominance, Scheffler says he now envisions a party in which "Republican state senators and state reps are expected to bite the bullet and not fall off the reservation on these issues." (McCain voted against a federal constitutional amendment in 2004 that would have banned same-sex marriage, calling it "un-Republican" because it took power out of states' hands.)

Opponents of the evangelical surge see Scheffler's rise to power as a sharp right turn that has already alienated all but the most clamorous opponents of abortion and same-sex marriage. Robert worries that ideology will trump attempts by this fellow moderates to mount successful centrist campaigns in swing districts. "They feel very shut out already," he said.

Allies of the Iowa Christian Alliance vigorously deny that the new party leadership will use any litmus tests in choosing to support local and statewide candidates. "That's a canard," scoffed Polk County chairman Ted Sporer. "That's sour grapes from the leadership class that's leaving power."

Scheffler, who says that his own perceived emphasis on social issues is overstated, downplays the "small differences" he may have with McCain. "We're not concerned with those. We're concerned with getting John McCain elected."

McCain backers acknowledge that the presumptive nominee's tendency to prickle at "values vote" flashpoints might privately chafe Scheffler, who once predicted a "bloodbath" if national Republicans were to nominate then-frontrunner Rudy Giuliani. But ultimately, McCain supporters say, the state Republican Party -- and Scheffler -- will support McCain's efforts there regardless of any ideological disagreements.

"He will do what he thinks is necessary to put McCain over the top," said a Republican who has worked with Scheffler for three political cycles. "There are conservative operatives who put rigid orthodoxy over victory. Steve Scheffler's not one of them."