WASHINGTON – House Republicans suddenly reversed course yesterday, deciding to retain a tough standard for lawmaker discipline and reinstate a rule that would force Majority Leader Tom DeLay to step aside if indicted by a Texas grand jury.

However, the closed-door GOP meeting made one ethics change that could make it easier for one party to block a House ethics committee investigation of a congressman. The provision would require a majority vote of the evenly divided committee to proceed with an investigation. The GOP voted to scrap the current system, which allowed an investigation to begin automatically if the two top committee leaders took no action on a complaint after 45 days. The proposals go before the full House today.

The rules changes include a decision to give new authority to the committee that oversees homeland security issues, a step that the September 11 Commission had strongly advocated.

The surprise dual decisions on the indictment rule and the discipline standards were engineered by Speaker Dennis Hastert and by Mr. DeLay – who asked GOP colleagues to undo the extreme act of loyalty they handed him in November. Then, Republicans changed a party rule so Mr. DeLay could retain his leadership post if indicted by an Austin grand jury.

When Republicans began their meeting last night, leaders were considering a rules change that would have made it tougher to rebuke a House member for misconduct. The proposal would have required a more specific finding of ethical violations.

Republicans gave no indication before the meeting that the indictment rule would be changed. Even more surprising was Mr. DeLay’s decision to make the proposal himself.

Jonathan Grella, a DeLay spokesman, said Mr. DeLay still believed it was legitimate to allow a leader to retain his post while under indictment. But Mr. Grella said that by reinstating the rule that he step aside, Mr. DeLay was “denying the Democrats their lone issue. Anything that could undermine our agenda needs to be nipped in the bud.”

Mr. Grella said Republicans did not know that Mr. DeLay would make the proposal. “He was doing some thinking and this was the conclusion he came to,” the spokesman said.

Mr. Hastert made the proposal to retain the current standards of conduct.

Rep. Mark Kirk, a Republican of Illinois, said, “It’s a mark of a leader to take a bullet for the team and not for the team to take a bullet for the leader. I’m very glad we decided to stick with the rules.”

Hastert spokesman John Feehery said that a change in standards of conduct “would have been the right thing to do but it was becoming a distraction.”

Brendan Daly, a spokesman for House Democratic Leader Nancy Pelosi, said Republicans pulled back on the discipline rule because “the issue simply became too hot for them to handle.”

Democrats yesterday toughened their own indictment rule. Previously, only committee chairmen were required to step aside if indicted. Now, the same rule applies to House Democratic leaders.