The president has officially announced his 2012 re-election campaign, and some say it'll be the most expensive in history. 

Last November, U.S. Rep. Michele Bachmann, R-Minn, beat her challenger to retain this congressional district. The race earned a high-dollar distinction. 

In last year's U.S. Senate race, U.S. Sen. Barbara Boxer, D-Calif., beat her wealthy opponent. It's been reported that the senator spent nearly everything she'd raised — 

Bloomberg was named mayor of New York City the third time in a row, having bested his 2009 challenger.

Democrat Sen. Harry Reid went all out to secure his Nevada Senate seat last year. This meant aiming for a lofty goal. It was the second-most-expensive Senate race —

Pataki was re-elected New York's governor in 2002, after spending somewhere in the ballpark of this large sum. 

Then-New York Sen. Hillary Rodham Clinton reportedly spent more than any other Senate candidate when she ran against her 2006 opponent. 

During the last midterm elections, Sen. John McCain, R-Ariz., is estimated to have spent more on a successful bid than any other Senate candidate.