In his announcement today, during which he was accompanied by Steve Forbes, Malpass called Gillibrand the "unelected occupant" of the Senate seat.
"She's chosen at every step to spend to spend New Yorkers' hard-earned taxes without setting any limits or boundaries," Malpass said.
In response, Gillibrand's campaign released a statement: "David Malpass not only helped cause the financial collapse, he made millions and left taxpayers holding the bill."
Malpass joins two other mostly unknown Republicans, former Port Authority board member Bruce Blakeman and Joe DiGuardi, who served in the U.S. House in the 80s.
Another Republican suspected to run, former Gov. George Pataki, announced today that he won't run. Instead, he's forming a group called Revere America which will work to repeal health care reform.