This year's campaign is headed toward an epic clash of Republicanism at the Cleveland convention this summer. But it's not the first time the party has been rocked by turbulence ahead of its convention. Again and again since 1912, splits between establishment GOP figures and the party's most ardent conservatives have hobbled the party's performance in November.
Here's a look at the drama that has come before:
Theodore Roosevelt returns four years after leaving the presidency to challenge the man who succeeded him with his blessing: William Howard Taft. Losing at the convention, TR runs as a Progressive, splits the Republican Party and brings about the election of Democrat Woodrow Wilson.
Ten names are placed in nomination at the Chicago convention, but none can get a majority. Ohio Sen. Warren Harding is interviewed by party leaders at 2 a.m. and nominated the next day on the 10th ballot. He wins in November, restoring Republicans to the White House.
Herbert Hoover extends GOP dominance into third White House term.
As Great Depression deepens, FDR defeats Hoover in a landslide.
Republicans assume they can deny FDR a third term but their convention is split between an Eastern establishment moderate (Thomas E. Dewey of New York) and a conservative (Robert A. Taft of Ohio, son of the former president). On the sixth ballot, the delegates turn to a third option. He is Wendell Willkie of Indiana, a public utility executive with no political experience who has risen in polls despite have entered no primaries. Willkie loses to FDR in an Electoral College landslide.
Dewey, who had been the nominee in 1944 (losing to FDR), returns as the front-runner. But he is once again opposed by Taft, the champion of the party's hard-core conservatives. It takes three ballots, but Dewey prevails, frustrating Taft's loyalists. In November, Dewey is upset by a resurgent Harry Truman, who has been president since FDR's death in 1945.
Taft forces come to Chicago confident their turn has come. But the Eastern establishment has found a new hero, a war hero, in Gen. Dwight D. Eisenhower, who has been serving as president of Columbia University in New York. The convention begins with a series of fights over rules and credentials, most of them regarding delegates from the South. Eisenhower comes up a few votes shy during the first ballot, but a shift away from a third candidate breaks a near-tie and frustrates the Taft faction once more.
Ike's vice president, Richard Nixon, has the votes to be nominated but there are two high-profile "favorite son" candidates: New York Gov. Nelson Rockefeller and Arizona Sen. Barry Goldwater. These inheritors of the Dewey-Taft rivalry both step aside for Nixon. "Let's grow up, conservatives," says Goldwater. "If we want to take this party back — and I think we can someday — let's get to work." Nixon loses narrowly in November to Democrat John F. Kennedy.
Goldwater's "someday" comes in the very next cycle, as his wins in key primaries in the West unhorse Rockefeller and the Eastern establishment. Rockefeller leads a walkout from the convention and Goldwater's acceptance speech declares war on moderates. Goldwater loses 44 states in November.
Nixon unites the party factions well before the convention, turning back an eleventh-hour bid from California Gov. Ronald Reagan. Nixon then wins one term narrowly and a second in a 49-state landslide before resigning in disgrace in 1974 because of the Watergate scandal.
Reagan returns to challenge incumbent President Gerald R. Ford (Nixon's vice president) for the nomination, reviving the Dewey-Taft wars of a generation earlier. With a late surge in Southern and Western primaries, Reagan cuts Ford's lead. But his attempt to break the convention open with rules changes comes up short by 111 votes. Ford wins on first ballot but loses in fall to Democrat Jimmy Carter.
Reagan loses Iowa to moderate George H.W. Bush, but wins New Hampshire, wraps up nomination in May and takes Bush as running mate. Reagan serves two terms, winning the second with 49 states.
Explicitly religious conservatives emerge as a major bloc, but Bush holds off a big field of primary challengers. Dividing the votes of conservatives, Bush wins on first ballot and takes 40 states in November.
Incensed by Bush's acceptance of tax increases in a budget deal, Patrick Buchanan challenges his renomination. Summoning the spirits of Taft, Goldwater and Reagan, Buchanan still fails to block a second Bush nomination but weakens the incumbent. Billionaire Ross Perot runs as an independent on Bush's right, helping Democrat Bill Clinton win with just 42 percent of the popular vote.
Buchanan again leads the charge from the right, but several others split the conservative bloc, and insider Bob Dole, the Senate majority leader who was Ford's running mate 20 years earlier, wraps up the nomination in March. He loses to Clinton in November.
Once again a large field forms, with 10 early candidates vying for the votes of "movement conservatives." Establishment voters coalesce around Texas Gov. George W. Bush, forcing out "maverick" challenger John McCain by the second week of March. Bush loses the popular vote to Vice President Al Gore but wins the Electoral College after the Supreme Court shuts down a recount in Florida.
McCain returns and dispatches rival Rudolph Giuliani, former mayor of New York, early in the establishment lane. Again there are 10 early contenders for the conservative mantle, but most drop either before or after the first primaries. Baptist minister Mike Huckabee is the last of them, withdrawing in early March. McCain names a conservative favorite, Alaska Gov. Sarah Palin, as his running mate. Their ticket gets less than a third of the Electoral College vote.
Former Massachusetts Gov. Mitt Romney renews his 2008 bid, this time as an insider favorite more than a conservative option. He easily dispatches other contenders to his left while more than half a dozen conservatives take turns leading in the polls. One, former Sen. Rick Santorum of Pennsylvania, wins Iowa and extends the struggle into May before conceding. Restive conservatives at the convention in Tampa are only partially placated by the choice of Wisconsin Rep. Paul Ryan as running mate.