Republican Senate candidate Pat Toomey says Congress could have avoided the housing market collapse if it had heeded his warnings to increase regulation of mortgage giants Fannie Mae and Freddie Mac back in 2003.
There's less than a month until the Nov. 2 election and Toomey and Sestak are in a competitive race to replace five-term Sen. Arlen Specter, whom Sestak defeated in the May primary.
Sestak decided not to seek re-election to his House seat while running for Senate.
Toomey spoke at a hotel in downtown Philadelphia on Wednesday and criticized Sestak for voting to bail out Fannie and Freddie.
A Sestak spokesman called Toomey's attacks unfounded. He says the Democrat voted in favor of more oversight for Fannie Mae and Freddie Mac as soon as he got into office.
(This version CORRECTS that Sestak decided not to seek re-election to House seat, instead of resigned.)