WASHINGTON (Reuters) - The chairman of the U.S. House Financial Services Committee, Ohio Republican Rep. Michael Oxley, could announce his retirement as early as Tuesday, sources close to the congressman said on Monday. Oxley's spokeswoman did not return calls for comment. Oxley most recently shepherded a bill through the House of Representatives to overhaul regulation of mortgage finance giants Fannie Mae and Freddie Mac. The bill must still clear the Senate, which is unlikely this year. Despite Congress being in session, Oxley has events scheduled in his home state on Tuesday. "There could be an announcement tomorrow in Ohio," said...