The House investigation into Rep. Charlie Rangel (D-N.Y.) took a major step forward Thursday as the House Ethics Committee announced it had broadened its inquiry into new information about the congressman's financial disclosure forms.

Rangel chairs the tax-writing Ways and Means Committee, but has admitted to failing to report up to $600,000 in income from rental properties. He is also a close ally of House Speaker Nancy Pelosi, who has been steadfast in her public support of Rangel, although Democrats privately lament the political water they're taking on as the Rangel matter takes on a higher profile at the same time as his committee considers health care reform.

Wednesday, House Republicans introduced a measure to strip Rangel of his chairmanship until the Committee of Standards and Official Conduct (formerly the Ethics Committee) completed its investigation into irregularities in his disclosure reports. Republicans see the growing Rangel scandal as a prime opportunity to turn the tables on Speaker Pelosi, who repeatedly accused them of engendering a "culture of corruption" during the 2006 and 2008 elections.

House Democrats defeated the measure and sent the matter back to the Ethics Committee, and members of the Congressional Black Caucus sent a letter to the speaker stating: "(Rangel) has our full support as the chairman of the Ways and Means Committee while this bi-partisan ethics review is pending."

The chairs of the Ethics Committee, Reps. Zoe Lofgren (D-Calif.) and Joe Bonner (R-Ala.) said that the bi-partisan panel had voted unanimously Thursday to expand its inquiry into the congressman. The investigation has already racked up 150 subpoenas, 34 witness interviews and 30 investigative subcommittee meetings.

Rangel's office issued a statement: "Today's action by the committee is a technicality, as everything they referenced in today's announcement has already been subject to ongoing review by the ethics committee and its staff. It is clear that the committee is being very thorough and deliberative in their process, hence today's announcement."

But House Minority Leader John Boehner (R-Ohio) countered, "The American people won't stand for having a chairman of the House's tax-writing committee who is under investigation for not paying his taxes. What more has to happen before Speaker Pelosi does the right thing?"