WASHINGTON — The arrest of Illinois Gov. Rod R. Blagojevich on Tuesday marked the latest in a series of scandals involving Democratic politicians -- an ironic turn for a party that won control of Congress in 2006 in part by saying it would end a "culture of corruption" under Republican leadership.
Democrats also highlighted Republican ethical problems in the successful bid to expand their congressional majorities this year, and Barack Obama made government transparency and a crackdown on lobbyist influence a theme of his presidential campaign.
The corruption charges against Blagojevich come as one of the most powerful Democrats in Congress, Rep. Charles B. Rangel of New York, chairman of the House Ways and Means Committee, is under investigation by a House ethics panel.
The panel is looking at Rangel's occupation of several rent-controlled apartments in Manhattan, whether he failed to pay taxes on an offshore rental property and other questions. On Tuesday, it announced that the investigation was expanding to include allegations that Rangel supported a tax break for an oil drilling company in exchange for a donation to a school that would bear his name.
Democratic Rep. William J. Jefferson of Louisiana is awaiting trial on charges of bribery, money laundering and misusing his congressional office. He has pleaded not guilty. On Saturday, Jefferson was ousted from his House seat in a runoff election.
Earlier this year, Democratic Gov. Eliot Spitzer of New York resigned after revelations that he was a regular customer of an elite call-girl ring.
The allegations against Blagojevich -- including that he solicited favors to influence his decision about who should replace Obama in the Senate -- were shocking to Democrats.
"It straightened my hair," said Rep. Debbie Wasserman Schultz (D-Fla.).
Democrats said they hoped the political fallout for their party would be limited, but they acknowledged the developments gave Republicans a political target during Obama's transition.
"Do I think Republicans will try to make something of this?" asked Rep. George Miller (D-Martinez). "Of course."
The new chairman of the GOP's Senate campaign committee was quick to respond to the Blagojevich news.
"Every Democratic and labor union official, whether in Illinois or in their national organizations, who has spoken with the governor or his aides about this U.S. Senate seat should step forward and immediately make public the full details of those conversations and meetings," said Sen. John Cornyn (R-Texas). "The stain of corruption needs to be lifted from this selection process and the public trust restored."
Obama said he had made no contact with the governor about his Senate replacement, but he said little else because the investigation was ongoing.
The political risk for Democrats is that voters will be as repulsed by the ethics problems as they were by the scandals that contributed to the defeat of former GOP Reps. Tom DeLay of Texas, Bob Ney of Ohio, Mark Foley of Florida and others.
Democrats won those and other House seats in districts that had been reliably Republican, and the party made ethics an issue in the 2006 elections that delivered control of Congress to Democrats.
But Rep. Chris Van Hollen (D-Md.), chairman of the committee responsible for helping elect Democrats to the House, said he thought the political damage would be limited to those engaged in wrongdoing because the party leadership had made ethics reform a priority.
By contrast, he said, DeLay and other Republican leaders systematically built ties between the party hierarchy and lobbyists.
Democrats hope the Blagojevich scandal will be dealt with quickly and decisively to avoid broader aspersions being cast on the party.
"You want these guys over the edge of the ship as fast as you can push them," said Peter Fenn, a Democratic political consultant. "This is something that Obama is going to have to be dealing with pretty fast."
House Speaker Nancy Pelosi (D-San Francisco) recently said she expected the Rangel investigation to wrap up by the end of this session of Congress. Now, with the inquiry expanding, it seems more likely to run into next year.
Republicans have called on Rangel to step down as chairman of the Ways and Means Committee, a panel that will have a big role in writing the economic recovery legislation that Obama has made a priority.