House Republicans got fresh ammo for their assault on embattled Ways and Means Chairman Charlie Rangel (D-N.Y.) with the Thursday revelation that the House ethics committee is once again expanding its probe of the Harlem Democrat.

But top House Democratic sources said the news was unlikely to weaken Rangel’s grip on his gavel. Instead, party leaders will hold to their mantra that the veteran lawmaker is innocent until proven guilty, that the ethics process is working and that it must be allowed to conclude.

“All this, at the end of the day, is going to be an issue of what the committee decides to do, and what the punishment is, if anything,— one senior House Democratic aide said.

The ethics committee, officially the House Committee on Standards of Official Conduct, on Thursday announced it is broadening its months-long look into Rangel’s tangled personal finances to include his August disclosure of more than $500,000 worth of assets that he failed to previously report. It came a day after lawmakers voted largely on party lines to beat back a Republican effort to strip Rangel of his chairmanship.

A Rangel spokesman dismissed the move by ethics as “nothing new.—

“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,— the Rangel spokesman said in a statement. “It is clear that the committee is being very thorough and deliberative in its process, just as the Chairman expected.—

Republicans, however, said the news provided further proof that Rangel needs to step aside until the investigation wraps. House Minority Leader John Boehner (R-Ohio) called it “past time— for Speaker Nancy Pelosi (D-Calif.) to remove Rangel from his perch.

“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,— he said in a statement. “What more has to happen before Speaker Pelosi does the right thing?—

And the captain of the GOP’s anti-Rangel push, Rep. John Carter (Texas), signaled Republicans will continue offering resolutions to force Rangel aside.

“We’ll continue to ask that he step down from his position until the investigation is complete and pressure Speaker Nancy Pelosi to do the right thing,— Carter said in a statement.

There was evidence on Wednesday that rank-and-file Democrats were starting to feel the heat from being forced again and again to go on record voting to protect Rangel. Two Mississippi Democrats — Reps. Gene Taylor and Parker Griffith — crossed over to support the Republican resolution. In part to ensure more didn’t break ranks, Democratic leaders changed their tactic for deflecting the measure, moving to refer it to the ethics committee, instead of simply tabling it as they have done on past resolutions targeting the lawmaker.

As he angles to weather the probe, Rangel benefits from Pelosi’s continued support and a deep well of goodwill from his colleagues, several Democratic aides said. The question is whether that support will hold up as the investigation drags on and Republicans look to keep the pressure on — and whether any new revelations will deepen Rangel’s ethics quandary.

The amended reports filed in August indicate that in 2006, Rangel sold a personal residence in Florida, which did not require disclosure because it was not an income-generating property. Rangel used the assets of that sale to purchase a Merrill Lynch account valued from $250,000 to $500,000. The following year, that account generated from $15,000 to $50,000 in income, but Rangel did not disclose the existence of the account or the income.

Similarly, Rangel’s amendments disclosed for the first time a Congressional Federal Credit Union account that the chairman has had since at least 2002, which generated thousands of dollars in income that he did not disclose. In 2007, for example, the credit union account was worth $250,000 to $500,000, generating from $5,000 to $15,000 in income, according to the amended reports.

The amendments indicate that Rangel’s personal net worth is far greater than he originally reported. The form Rangel originally submitted for calendar year 2006 indicated that he had assets worth a minimum of just more than $200,000. The amended form for that year lists assets worth a minimum of just more than $800,000.

— Paul Singer contributed to this report.