Feb. 1, 2012 -- intro: Republican presidential campaigns released their quarterly filing reports Tuesday, showing that the four remaining campaigns have already spent millions in the battle for the Republican nomination.
But only one can win, and for the losers and their donors, that's millions gone down the drain.
It's no doubt that running for president is an expensive endeavor. Riding caravans of campaign buses and jet-setting from state to state for each primary and caucus -- not to mention the campaign ads, candidates' personal wardrobes and campaign staff salaries -- all tend to add up.
While the amount candidates can raise is limited if they choose to accept public campaign financing, they can spend an unlimited amount if they stick to private donations and funding.
ABC found the top-five most expensive failed primary campaigns of the past decade, based on campaign finance reports to the Federal Election Commission. One of the top spenders might be a name you've heard recently.
quicklist: 1title: Hillary Clinton, 2008 - $250,660,755url: 15483044text:
The highest spender on an unsuccessful bid in a presidential primary was former Senator for New York Hillary Clinton, whose campaign forked over more than $250 million through the end of 2008.
The Clinton campaign reported more than $22.5 million in debts and obligations at the end of June 2008, thought to be the highest campaign debt in history.
Not only her campaign, but also Clinton, personally, lost on the venture. She contributed a $13.2 million loan to her own campaign that she later wrote off in efforts to make good on the campaign's outstanding debts.
By the time Clinton suspended her presidential campaign June 7, 2008, the Obama campaign had spent about $6 million less than Clinton's, or about $244 million.
quicklist: 2title: Mitt Romney, 2008 - $113,627,217url: 15483044text:
Former Massachusetts Gov. Mitt Romney's campaign in the 2008 Republican primary was the second-largest spender of unsuccessful primary campaigns in the past decade. By the end of 2008, its disbursements totaled more than $113.6 million.
For this year's race, Romney's campaign had dished out a total of $37,209,679.41 by the end of 2011, according to Tuesday's Federal Election Commission filing.
At that point four years ago, his campaign reported having spent more than twice as much, more than $86 million.
Romney's 2008 campaign won the second-highest number of delegates after Sen. John McCain, R-Ariz., but by a wide margin of 1,093 delegates.
Romney dropped out of the 2008 race Feb. 7, at which point McCain's campaign, John McCain 2008 Inc., had spent more than $40.5 million.
quicklist: 3title: Steve Forbes, 2000 - $86,027,058url: 15483044text:
Famous businessman and editor of Forbes magazine, Steve Forbes, ran in the Republican primary in 2000, and his unsuccessful campaign spent more than $86 million throughout his time in the race.
He did not come close to winning, losing all the state primaries or caucuses in which he participated.
But Forbes stayed in the race until February, at which point the eventual Republican nominee, George W. Bush, had spent more than $12.6 million.
quicklist: 4title: Rudy Giuliani, 2008 - $65,723,001url: 15483044text:
Former New York Mayor Rudy Giuliani's 2008 campaign in the Republican presidential primary spent more than $65 million by the end of that year.
Giuliani withdrew his candidacy after the Florida primary of that year, at which point Republican primary winner John McCain had spent more than $40.5 million.
Giuliani's campaign ended in considerable debt of more than $2 million. While he did not put up personal finances to help his campaign during his run for the nomination, he did loan personal funds later to assuage the debt his campaign had accumulated.
quicklist: 5title: John McCain, 2000 - $58,268,235url: 15483044text:
The 2000 campaign to elect Sen. John McCain, R-Az., spent nearly $58.5 million through the end of 2000, making it the fifth-highest spender of unsuccessful primary campaigns from the past decade.
McCain pulled out of that race March 9, at which point George W. Bush's campaign had spent more than $25 million, less than half he amount McCain's had.