It's something Californians know, having rejected a number of rich candidates, and something President Barack Obama can attest to; his path to Washington was paved in 2004 when he beat a wealthy rival who spent $30 million in a U.S. Senate primary. Bloomberg, a billionaire, spent more out of pocket, about $100 million, than any political candidate in U.S. history. Yet he won an embarrassingly thin victory Tuesday over Comptroller William Thompson, a candidate so obscure that two days before the election, in an admittedly unscientific New York Daily News survey, only eight of 20 voters could name Thompson when shown a color photograph. If the five-point win over his Democratic opponent chastened Bloomberg, he wasn't admitting it. On Thursday, standing in the city's main trouble-shooting hotline center, where workers field calls about everything from potholes to barking dogs, he dismissed suggestions the City Council or other politicians might see his showing as an invitation to buck the mayor. Recapping themes from his campaign, Bloomberg said his administration 'has an awful lot to build upon' as he struggles with the economy and fights to keep crime down. When his term is over, he said, after 12 years in office, 'I think people will say `Mike was right.' ' Students of local politics agreed that Bloomberg's much smaller-than-expected victory won't necessarily translate to problems running the nation's biggest city. He will face enhanced scrutiny from the new comptroller and public advocate, both Democrats, who criticized Bloomberg for fighting to reverse the city's two-term limit, allowing him to stay in office. (Both are believed to be eyeing a run for mayor in four years.) But 'the bottom line is, one vote is a mandate,' said Doug Muzzio, a political scientist at Baruch College. 'He is the mayor.' That gives Bloomberg control over a massive bureaucracy and the considerable powers that accrue under the city charter. His personal fortune, hardly dented by his lavish campaign, will allow Bloomberg to continue to contribute millions of his own dollars to civic and other organizations that indirectly help garner support. Picking through the election returns, analysts saw several reasons for the mayor's extravagant comeuppance, including an anti-incumbent climate and the sobering state of the economy, which fostered resentment among some put off by Bloomberg's exorbitant spending. (The Daily News figured he spent $157.27 per vote, to Thompson's $13.12.) 'At some point you have convinced all the people you can convince,' said Jennifer A. Steen, a lecturer at Yale and author of a book on self-financing candidates. 'The room for impact ... was very limited.' Bloomberg was not the only free-spending candidate to feel the sting of Tuesday's electorate. Across the Hudson River, New Jersey Democratic Gov. Jon Corzine was defeated by Christopher Christie even though he kicked in more than $22 million of his own money and out-spent his Republican rival by about 3-to-1. In Houston, mayoral candidate and City Councilman Peter Brown spent more than $3.2 million of his family wealth, yet failed to make the run-off. Spending huge sums of their own money gives political candidates certain advantages: the assurance they can buy name recognition, an image of independence from special interests and, not least, the freedom from having to spend big chunks of time scaring up cash. 'You don't have to attend one endless fundraiser after another, shifting from one foot to the other, eating hors d'oeuvres you don't really need, having conversations you don't really want to have, all so people will give you money to pay for advertising,' said Darry Sragow, who managed Al Checchi's unsuccessful 1998 bid for California governor. Checchi, a former corporate executive, spent about $40 million on his losing campaign, placing him in the company of several other candidates who parted with millions in a vain attempt to win the California governorship or a seat in the U.S. Senate. Any political neophyte with an open checkbook faces inherent hurdles, said Paul Maslin, a Democratic strategist who has worked for wealthy candidates (Ross Perot, who spent $63 million in 1992 running for president) and those who faced them (Gray Davis, who beat Checchi in the 1998 Democratic primary.) 'There is always a suspicion,' Maslin said. 'Why are you really doing this? Do you have to conquer something else? Have you gotten bored with your life? Do you think somehow you don't have enough power?' The near-meltdown of Wall Street and the bankruptcy of corporate giants such as General Motors present wealthy candidates with an added layer of skepticism, Maslin suggested: 'How did they make their money and are they really in it for the good of society?' (Begin optional trim) Bloomberg, who earned a fortune in the news and information business, is by now a well-established officeholder. Still, his performance Tuesday showed that in politics, like economics, there is a point of diminishing returns. Two days after the election -- just 26 percent of eligible voters cast ballots -- a New York Magazine on-line chat site was still drawing responses from readers angry over the mayor's bludgeoning campaign. 'Honestly, I nearly voted against him solely due to the incessant mailings,' one said. 'The people he hires must certainly know that there's a threshold from informative to annoying,' another New Yorker wrote, 'and then from annoying to, `I'm voting against this guy just because of this.' ' (End optional trim) Barabak reported from San Francisco. 