The FBI is doubling the number of agents assigned to the Justice Department probe into alleged leaks by White House officials of the identity of CIA operative Valerie Plame.

As Democrats accused the White House of trying to improperly influence an inquiry into a leak, officials said on Thursday that the F.B.I. was doubling the number of investigators on the politically charged case.

The Federal Bureau of Investigation plans to use about 12 agents and other personnel, twice the number first planned, to try to find the person who leaked the identity of an undercover C.I.A. officer, the officials said.

It can quadruple them and it won't solve the problem. Bush and McClellan's remarks last week claiming that Rove, Abrams and Libby were not involved illustrate the need for special counsel. Four senators, in a letter written to Bush yesterday,

...pointed to the White House statement about the aides as one of several serious missteps. Mr. McClellan did not have the legal expertise to question possible suspects, said the letter from the Senate Democratic leader, Tom Daschle of South Dakota, and Senators Joseph R. Biden of Delaware, Carl Levin of Michigan and Charles E. Schumer of New York.

"The White House has now put the Justice Department in the position of having to determine not only what happened, but also whether to contradict the publicly stated position of the White House," they said.

Here's more on the Senators' letter to Bush.

Former federal prosecutor James Orenstein today joins the growing list of those calling for the appointment of special counsel.