House Judiciary Committee Chairman John Conyers writes, per TPM:

Dear Mr. Chertoff:

I was startled to read in today's Associated Press that a "federal law enforcement official" has leaked information about an immigration case involving a relative of Senator Obama. Even more troubling, the AP reports that it could not "could not establish whether anyone at a political level in the Bush administration or in the McCain campaign had been involved," a very disturbing suggesting indeed. This leak is deplorable and I urge you to take immediate action to investigate and discipline those responsible.

I note that this is not the first leak of law enforcement information apparently designed to influence the coming Presidential election -- in recent weeks law enforcement sources leaked information about an alleged investigation of a community services organization, a leak that the Department of Justice informs me is now under investigation by the Department's Office of the Inspector General and Professional Responsibility.

Such leaks are deeply harmful to the political process, and the American people expect and deserve better from their government and its law enforcement agencies.

Sincerely,

John Conyers, Jr.