A new call to censure President Bush for authorizing warrantless wiretapping of Americans as part of the war on terror may have less impact on Mr. Bush than on contenders for the Democratic presidential nomination in 2008, such as Senator Clinton, according to political analysts.

Senator Feingold of Wisconsin, who is among the Democrats exploring a presidential bid, said he will introduce a censure resolution in the Senate today.

"It's an unusual step," Mr. Feingold said yesterday on ABC's "This Week" program. "It's a big step, but what the president did by consciously and intentionally violating the Constitution and laws of this country with this illegal wiretapping has to be answered."

Republicans in Congress quickly dismissed the censure suggestion.

"I think it's a crazy political move," the Senate majority leader, William Frist of Tennessee, said on the same broadcast.

Senator Warner of Virginia warned that talk of censure could undermine Mr. Bush's ability to deal with foreign governments. "That was political grandstanding and it tends to weaken our president," Mr. Warner said during an appearance on CNN.

Mr. Feingold's proposal to censure Mr. Bush, which drew no immediate support from other lawmakers, seems to have little prospect of passing through the Senate or the House, both of which are under Republican control. However, it could step up pressure on prominent Democratic figures to accede to liberal activists who are intensifying their calls for stronger rhetoric and action against Mr. Bush.

"It's a problem for the Democrats more than the president or the Republicans, is the irony of the thing," a political analyst at George Washington University, Stephen Hess, said in an interview yesterday. "It forces a lot of Democrats, notably Hillary, to a position where, is she going to pander, is she going to get her back up and resist it, or is she just going to ignore it?" he said. "It's hard to ignore it."

Whether or not Mr. Feingold's proposal ever gets to a vote, some activists indicated yesterday that they will demand that Democratic senators make clear their stance on the question.

"It goes without saying, though, that there better damn well be 44 co-sponsors on Feingold's resolution," a user called Georgia10 posted on the popular left-wing blog DailyKos.com within minutes of Mr. Feingold's television appearance.

One Democratic political organizer, Joseph Trippi, told The New York Sun that Mr. Feingold's call will require some response from other contenders for the 2008 nomination.

"Regardless of the public opposition and of how many people roll their eyes, this is pretty serious stuff," Mr. Trippi said. "I think it's going to have an effect on the rest of the field."

Mr. Trippi said he thought Mr. Feingold's motivations were sincere and consistent with his long track record in favor of civil liberties. The senator is already popular among online activists, sometimes called the "netroots," and will gain ground with his latest move, the analyst said.

Mr. Trippi warned that any potential candidate who dismisses the censure idea risks being flamed online. "Anybody who says this is going too far is somebody who's probably writing off that side of things," he said. "Anybody who writes off the netroots or says you don't have to pay attention is really playing with dynamite."

Mrs. Clinton, who is running for reelection to the Senate this year, is the leading choice of Democrats in early opinion surveys about the 2008 race. She was favored by 39% of respondents in a CNN/USAToday/Gallup poll taken in February. Mr. Feingold polls in the low single digits, when pollsters bother to ask about him.

Aides to Mrs. Clinton had no comment yesterday on Mr. Feingold's resolution. Spokesmen for other Democratic presidential contenders did not respond to interview requests yesterday.

Some observers said the censure call created a dilemma for Democratic presidential hopefuls similar to the one they faced in January when Senator Kerry of Massachusetts called for a filibuster against the nomination of Justice Alito to the Supreme Court. Many analysts criticized Mr. Kerry's move as futile and unwise, but most Democrats, including Mrs. Clinton, grudgingly went along with it.

Another Democratic operative, Daniel Gerstein, said his party's candidates need to proceed cautiously with rhetoric condemning the president. "If all people hear about your message is you're against taking all reasonable measures to protect the country from terrorism and you don't want the CIA listening to Al Qaeda, it puts us in an even deeper hole on this issue," he said.

"Frankly, this is a free shot for Feingold. If I were him, I'd probably do the same thing. It's a very strong statement of principled opposition and he's playing to his base of support," said Mr. Gerstein, who is no relation to this reporter.

Analysts said some moderate Democratic contenders for the nomination, such as Senator Bayh of Indiana, Governor Thomas Vilsack of Iowa, and a former governor of Virginia, Mark Warner, might oppose the censure resolution.

"It's not a good choice for the Hillarys, the Bayhs and the Mark Warners of the world," Mr. Gerstein said. He noted that Mrs. Clinton has largely resisted pressure from the left to push for a rapid withdrawal of troops in Iraq.

The proposal Mr. Feingold is to introduce today reads, "Resolved, that the United States Senate does hereby censure George W. Bush, president of the United States, and does condemn his unlawful authorization of wiretaps of Americans." The measure alludes to a surveillance program that Mr. Bush authorized in 2001 to wiretap some communications between alleged Al-Qaeda affiliates and persons in America, without court oversight. The program operated in secret until December 2005, when its existence was disclosed by the New York Times.

Late last year, Rep. John Conyers, a Democrat of Michigan, introduced a resolution to censure Mr. Bush for misleading the country in connection with the war in Iraq and for allowing the torture of prisoners in Iraq. As of yesterday, the measure had 15 co-sponsors, including five New York Democrats, Reps. Maurice Hinchey, Jerrold Nadler, Carolyn Maloney, Major Owens, and Charles Rangel.

Mr. Conyers has also introduced a resolution to set up a House committee to consider the possible impeachment of Mr. Bush. The measure, which focuses primarily on issues relating to the Iraq war, has 29 co-sponsors, all of whom are Democrats.

A poll conducted in January by Zogby International found 52% of Americans agreed that Congress should consider impeachment "if President Bush wiretapped American citizens without the approval of a judge." About 43% of respondents said they disagreed with exploring impeachment.

Asked yesterday if impeachment proceedings should be instituted against Mr. Bush, Mr. Feingold said, "This is right in the strike zone of the concept of high crimes and misdemeanors." When pressed, the senator suggested he does not favor impeachment. "We have to consider: Is it best for the country to start impeachment proceedings? Is it best for the country to consider removing the president from office?"

Mr. Feingold is scheduled to visit New York on Saturday to attend an awards dinner at a Jewish synagogue in Park Slope.

One of Mrs. Clinton's opponents this year in the Democratic primary for her Senate seat, Jonathan Tasini, endorsed Mr. Feingold's call but said it didn't go far enough. "I still believe the House Democrats should be filing articles of impeachment next week," Mr. Tasini said.

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