He said the congressman needed a few days to think about the decision after word got out Friday that he was in negotiations with House Speaker Dennis Hastert to relinquish the post.
"Congressman Ney continues to believe he will be vindicated and he hasn't done anything wrong," spokesman Brian Walsh said Sunday.
Ney is at the center of the Justice Department's ongoing corruption probe and was identified by lobbyist Jack Abramoff in his guilty plea earlier this month.
The Administration Committee controls disclosures of lobbying practices and would be a key part of efforts to reform the system.
Walsh said Ney did not want to become a distraction as the Republican Party tries to reform Congress' relationship with lobbyists and special interests.
Ney will maintain his chairmanship of a Housing subcommittee, Walsh said.
A GOP leadership aide said Friday that Hastert was pressuring Ney to step aside because he believes it would be inappropriate for him to head the committee with jurisdiction over the Republican reform agenda.
Ney said after that disclosure Friday that he was thinking about stepping aside because he did not want to get in the way of Congress continuing its work.
The GOP aide, who spoke Friday on condition of anonymity because of the sensitivity of private talks between Ney and Hastert, said the speaker himself could not fire Ney, and unless Ney stepped aside it would be at least three weeks until the GOP caucus could consider removing him.
Ney continues to maintain that he has done nothing wrong.
Among other accusations, Abramoff said Ney took favors including a 2002 golf trip to Scotland, free dinners and events and campaign donations in exchange for his support of Abramoff's American Indian tribe clients in Texas and the lobbyist's purchase of a fleet of Florida casino boats.
Court papers released as part of Abramoff's plea to charges of conspiracy, mail fraud and income tax evasion detailed lavish gifts and contributions that Abramoff says he gave an unnamed House member, identified elsewhere as Ney, a Republican from Ohio.
Other accusations include that Ney supported legislation to help a California Indian tribe with taxes and a post office and, as chairman of the Administration Committee, approved a lucrative deal for an Abramoff client to improve cell phone reception in House buildings.
Ney's decision comes as House and Senate Republicans scramble to devise a plan that would go well beyond current rules governing travel, gifts and lobbying by former members of Congress and their aides, as part of an effort to curtail the influence of lobbyists on lawmakers.
Ney was elected to Congress from an expansive, rural district in 1994. He won a sixth term in 2004 with 66 percent of the vote, was unopposed in 2002 and hasn't earned less than 60 percent in any election since 1996.