PHILADELPHIA — Republican Senate candidate Pat Toomey on Wednesday attacked his Democratic rival, Joe Sestak, for Sestak's votes in support of the bailouts of mortgage giants Fannie Mae and Freddie Mac — and said he had warned of the housing crisis years ago.

Toomey, a businessman who served in the U.S. House from 1999 to 2005, said Congress could have avoided or greatly mitigated the housing collapse if it had passed a bill he co-sponsored in 2003 that would have increased government regulation over Fannie and Freddie.

"Congressman Sestak sold taxpayers out in order to pursue his left-wing agenda," Sestak said at a campaign event at a downtown hotel, adding the bailout of Fannie and Freddie cost $148 billion. "He now wants taxpayers to pay for his mistakes."

Toomey and Sestak are locked in a hypercompetitive race to replace five-term Sen. Arlen Specter, whom Sestak defeated in the May primary after deciding not to run for re-election to his suburban Philadelphia congressional seat while he ran for Senate.

Sestak spokesman Jonathon Dworkin called Toomey's attacks unfounded and said Sestak — a former Navy admiral — voted in favor of more oversight for Fannie Mae and Freddie Mac as soon as he got into office, in May 2007.

"Congressman Toomey likes to point the finger at everyone except himself, but he can't hide from the fact that he has always sided with Wall Street," Dworkin said in a statement. "Toomey supported the reckless Bush spending and aggressive dismantling of Wall Street safeguards that created this mess .. . He also did nothing to improve oversight of Fannie Mae and Freddie Mac."

Dworkin said Toomey also could have done more to stop predatory lending and protect consumers.

Toomey said legislation he co-sponsored in 2003, which ended up languishing, would have limited the size of single-family mortgages Fannie and Freddie could purchase and transferred regulatory authority over Fannie and Freddie from the Department of Housing and Urban Development to the Treasury Department — among other things.

He also said he repeatedly issued warnings about the risks posed by Fannie and Freddie.

"I was then raising a red flag," he said.