Not a great day for Rep. Pete Visclosky.

First, he announces that, amid a federal probe of a lobbying firm to which he has close ties, he's handing off responsibility for a key appropriations bill. Now, the Northwest Indiana Times reports that, according to a spokesman for the Indiana Democrat, his top aide has unexpectedly "retired."

The aide, chief of staff Chuck Brimmer, will be replaced by district director Mark Lopez, said Visclosky's office.

Last week, Visclosky revealed that he had been subpoenaed for documents in connection with the probe, which is focused on whether the now-defunct PMA lobbying firm gave campaign contributions in exchange for earmarks. Visclosky has taken almost $200,000 from donors with ties to PMA. Last year he got more than $20 million in earmarks for the firm's clients.