The rapidly growing scandals surrounding tainted lobbyist Jack Abramoff now involves four members of Congress, several former and current congressional aides and two former Bush administration officials.

Prosecutors in the Justice Department’s public integrity and fraud divisions are looking into Abramoff’s dealings with four Republicans — former House of Representatives Majority Leader Tom DeLay of Texas, Rep. Bob Ney of Ohio, Rep. John Doolittle of California and Sen. Conrad Burns of Montana.

Abramoff, long known as one of Washington’s most shady operators, is under investigation over his lobbying efforts for Indian tribes with casinos. He has also pleaded not guilty to federal charges in Florida that he defrauded lenders in a casino cruise line deal.

The prosecutors are also investigating at least 17 current and former congressional aides, about half of whom later took lobbying jobs with Abramoff, as well as an official from the Interior Department and another from the government’s procurement office.

Justice Department spokesman Paul Bresson declined to comment on the investigation.

Investigators were looking into whether Abramoff and his partners made illegal payoffs to the lawmakers and aides in the form of campaign contributions, sports tickets, meals, travel and job offers, in exchange for helping their clients.

DeLay and Ney have already retained criminal defense lawyers.

Michael Scanlon, a former aide to DeLay and partner to powerful Republican lobbyist Abramoff, pleaded guilty to conspiracy on Monday under a deal in which he is cooperating with prosecutors probing the alleged influence-buying.

Scanlon left DeLay’s office and become a partner to Abramoff, who has been indicted for fraud in a separate case in Florida. The plea agreement has been seen as a major advance in prosecutors’ efforts to investigate the lobbyist.

The spreading scandal has sent shock waves through the GOP, which is already reeling from numerous other scandals and the growing problems of the Bush administration.

“This is not good,” admits one longtime GOP consultant. “A lot of people could have their ass in a sling over this.”