WASHINGTON, 28 May — During the Watergate hearing 30 years ago, Sen. Howard Baker (R-Kansas) famously asked: “What did the president know, and when did he know?”

Earlier this month, as news surfaced that President George W. Bush had been briefed in August on the possibility of terror attacks similar to the ones perpetrated on Sept. 11, his political opposition has repeated the question.

But the famous query that signaled the downfall of President Richard Nixon in 1974 has failed to diminish Bush’s popularity, prompting the Democratic leadership to retreat from its assault on the White House and worrying many in the party that the upcoming mid-term elections will be disastrous.

On Sunday, Senate Majority Leader Tom Daschle (D-South Dakota) recanted his May 16 charge that President Bush had advance warning of last autumn’s terror attacks on the Pentagon and New York’s World Trade Center. “We were told on that particular morning that the president had received a particular set of facts that he may or may not have received. He has denied having received that information. And we accept that,” Daschle said on NBC’s “Meet the Press.”

Daschle added: “If he says he didn’t receive it, I’m not going to challenge that. What I’m going to say is, why didn’t he receive it?”

His revised attack on the Bush White House stands in stark contrast to what Daschle said two weeks ago, when he declared: “I’m gravely concerned about the information provided us just yesterday that the president received a warning in August about the threat of hijackers by Osama Bin Laden.”

The backtracking by Daschle comes one week after House Minority Leader Richard A. Gephardt (D-Missouri), abandoned earlier statements suggesting that Bush had warnings before Sept. 11 that might have prevented the deadly terrorist attacks.

The “flip-flop” in Daschle’s attack on the White House underscores frustration felt by many Democrats with President Bush’s popularity. Many leaders in the Democratic Party are squabbling over their campaign agenda, retreating on some issues and losing support at the party’s base five months before the midterm elections.

With the battle for control of Congress turning on relatively few close races for the House and Senate, the Democrats are arguing among themselves about what they should stand for and searching for issues to use against Bush and the Republicans in the fall campaigns.

Embarrassed by what now appears to be an ill-advised assault on Bush, Democratic strategists are criticizing their leadership’s decision to attack the administration on what opinion surveys show as its strongest ground. The thinking now among Democratic leaders is to stick to domestic social-welfare issues and cede national security issues to Bush.

In a strongly worded memorandum last week, the Democratic Leadership Council criticized Democratic leaders for being so accusatory in attacking Bush. “The Watergate language used by some congressional Democrats, suggesting a gleeful partisan effort to assign blame for 9/11, is neither credible nor constructive,” the memo said.

Even Democratic voters, by a margin of 37 percent to 33 percent, preferred the administration’s approach to the war on global terrorism to their own party’s proposals, according to a Pew Research Center poll.