Ron Paul's announcement Monday that he will stop actively campaigning in the 11 remaining Republican primary states puts him within inches of becoming the eighth major presidential candidate to fall to Mitt Romney in this election.
If and when Paul decides to officially call it quits, his failed White House bid will have cost his backers more than $40 million, including spending from Paul's campaign and the super PAC supporting him.
Indeed, those eight candidates' campaigns spent a combined total of $132.7 million trying, and failing, to beat Romney in the GOP primary, according to an ABC News analysis of campaign disclosure data from the Center for Responsive Politics.
The number shoots up to $174.4 million in bad investments when super PAC spending to support those candidates is taken into account.
Here's a look at the hefty cost of failure that comes with running an unsuccessful presidential campaign.
Rep. Ron Paul's third White House bid has been his most expensive yet. In his 2008 bid for the White House he pulled in $34 million and, despite being a lesser-known candidate, set the record for raising the most money in a single day during that election, according to the Center for Responsive Politics.
This time around, Paul's campaign has spent $35 million so far, financial disclosures show. Pro-Paul super PAC Endorse Liberty shelled out $3.6 million for its candidate and the Revolution PAC spent $1.2 million to support Paul.
After $40 million in expenses and advertising, Paul did not win a single state's primary.
He did raise his national profile a bit. An MSNBC poll shows that in the six-month span between October and March, while Paul was crisscrossing early primary states, the number of people who said they didn't know his name or had no opinion of him decreased from 24 percent in October to 13 percent in March.
And with $40 million already out the door, campaign spokesman Gary Howard said winding down Paul's campaign "was a financial consideration, definitely."
When Newt Gingrich conceded defeat in the Republican primary earlier this month, his campaign was 10 days short of its 1 year anniversary. In Gingrich's 355 days on the trail, his supporters invested more than $31 million in his failed presidential bid.
A hefty portion of that campaign cash came from billionaire Sheldon Adelson. Together with his wife, Adelson bankrolled pro-Gingrich super PAC Winning Our Future, pumping $20 million into the unlimited expenditure political action committee.
Such a large chunk of the casino billionaire's change helped propel Gingrich to victory in only two states: South Carolina and his home state of Georgia.
As of the most recent campaign finance report deadline March 31, the super PAC for the now-defunct candidate was still sitting on more than $5 million, which it can spend on pretty much whatever it wants.
Rick Santorum was known for his shoestring-style of campaigning. He drove a buddy's pick-up truck to all 99 counties in Iowa. He scrapped the idea of a national campaign headquarters in favor of a work-from-home approach. And he forwent the quintessential campaign bus for the majority of his campaign.
But for all his frugality, the unsuccessful Republican candidate still spent close to $27 million on his primary bid. More than half of the $20 million his campaign raised came from small donors, those who gave less than $200, according to the Center for Responsive Politics. But, similar to Gingrich, Santorum got some major financial help from one wealthy and generous donor.
In Santorum's case, that campaign sugar daddy was millionaire Foster Friess, who dumped $2.1 million into Pro-Santorum super PAC The Red, White & Blue Fund.
As of March 31, Santorum's campaign had about $2 million cash on hand. The super PAC supporting him had about $200,000 left in the bank.
While the $26.8 million Santorum and his allies spent on his failed presidential bid did not land the former Pennsylvania senator in the White House, they did boost his national profile.
ABC News-Washington Post polling shows that in January about 44 percent of those polled had no opinion of Santorum. By mid-March, that number of undecideds had dropped to 25 percent.
As a presidential candidate, Texas Gov. Rick Perry presided over a group of fundraisers whose pockets were as deep as his Texas roots. A full 96 percent of Perry's campaign donations came from large donors, or those who gave more than $200, according to the Center for Responsive Politics.
Throughout his five-month campaign, Perry squandered $19.3 million while the super PAC supporting him shelled out $5.4 million. The governor lost the two states in which he competed.
When he left the race, about 22 percent of people nationwide still either did not know who he was or did not have an opinion about him, according to an MSNBC poll.
While Perry, Santorum and Gingrich all had multimillion-dollar super PACs supporting their candidacy, Herman Cain relied almost entirely on donations directly to his campaign.
The former Godfather's pizza CEO drained his $16.6 million war chest in the seven months leading up to the first primary votes. But amid sexual harassment allegations, Cain dropped out of the GOP race one month before the first votes were cast.
The $17 million that supporters spent on his failed primary bid were not entirely fruitless. After all, without Cain, the phrase "9-9-9" would have far less significance in national politics.
Cain has vowed to continue the push for his 9-9-9 tax plan, rolling his White House bid into an advocacy campaign for lower, flatter taxes. While so far his group Sick of Stimulus hasn't gained much footing, it has produced some notable videos.
|Jon Huntsman Jr.|
Former Utah Gov. Jon Huntsman left his post as the U.S. ambassador to China, in part, to run for president. But despite $11 million and more than six months of campaigning, Huntsman never mustered more than about 3 percent support nationally.
More than half of the $8 million his campaign raised came from Huntsman himself and $2.2 million of the $3.1 million that pro-Huntsman super PAC Our Destiny spent was donated by Huntsman's father.
Forbes estimates that the former governor is worth about $50 million, mere pennies compared to the more than $1 billion estimated net worth of his father, who founded the global chemical company Huntsman Corp.
While that multimillion-dollar investment did not propel Huntsman to primary glory, it exponentially raised the profile of his three oldest daughters. Abby Huntsman Livingston, 26, now appears regularly as a pundit on cable news and, along with sisters Liddy and Mary Ann, is something of a Twitter icon.
Michele Bachmann, a Tea Party-movement darling originally from Iowa, came out of the gate with a vengeance, taking the August Iowa straw by storm. She raked in more than $9 million for her campaign mostly from small donors who gave less than $200.
But while she posted impressive fundraising numbers early on in her campaign, as her momentum quickly dissipated, she ended up raising less for her presidential bid in 2012 than she did for her congressional bid in 2010, according to the Center for Responsive politics.
Pro-Bachmann super PAC MICHELE PAC, raised and spent about $1 million to support her.
Former Minnesota Gov. Tim Pawlenty's presidential race was short, sweet and (comparatively) inexpensive. His three-month flirtation with the GOP primary cost his supporters about $5.2 million.
That is a mere fraction of the $7 million, on average, that Romney's campaign has spent per month throughout his 11-month-long candidacy. It should be noted, of course, that Pawlenty's relatively low-cost campaign was waged long before the candidates began pouring millions into advertising.
Pawlenty did not leave the campaign trail when he ended his campaign. He is now a strong Romney supporter, often appearing at Romney rallies. He is rumored to be on Romney's short list of vice presidential possibilities.