David Letterman told a joke the other night about incompetent politicians, and it went like this: "More Americans can name the Three Stooges than the three branches of government . . . because the Three Stooges are more likely to get something done."

The audience roared, and no wonder: The conventional wisdom these days is that the incumbents in Washington, starting with the people at the White House, seem generally incapable of doing their jobs effectively. This perception is potentially most damaging to the Republicans, since they run Washington. And national polls suggest that two issues, both involving well-documented failures of execution, have been pivotal: Iraq and Katrina.

Iraq tends to get more attention, because of the ongoing death toll and the growing specter of civil war. But with the first anniversary of Katrina, and with the government scrambling to put the best face on its sluggish reconstruction efforts, it is clear that the White House has yet to recover from the thumbs-down verdict that was rendered nearly one year ago in the court of public opinion. And this has put the GOP's congressional majorities in jeopardy, with elections on tap in November.

Pollster Andrew Kohut, who directs the nonpartisan Pew Research Center for People & the Press, said the other day: "Katrina has strongly fed the general perception that Washington isn't working, that this president is not a strong leader, and that Congress isn't getting things done. And that's dangerous for many of the Republicans who are running this year to keep their jobs."

Larry Sabato, a nonpartisan analyst who closely tracks congressional races, said: "Midterm elections are a perfect vehicle for voters to send a dramatic message. This year, the likeliest message will be a direct result of Katrina.

"When Bush ran for president, he touted 'leadership' and 'competence.' The idea was, you didn't have to agree with him, but at least he knew what he was doing. Katrina delivered a knockout blow to that image. To independent swing voters, now he's the guy who 'can't deliver.' That's one reason why Republican incumbents could get burned this year. They share party affiliation with an unpopular president."

Many Bush defenders frankly acknowledge the sour public mood, and note the fact that FEMA (the much-maligned Federal Emergency Management Agency) has become a national punch line on late-night TV.

Conservative commentator Jonah Goldberg believes "there is a hunger for competence out there," that Americans long "for a problem-solver on a white horse (as) a response to Bush's record." In fact, some '08 presidential hopefuls — such as Democrat Mark Warner and Republican Mitt Romney — are touting their gubernatorial records as proof that they know how to roll up their sleeves to get things done. In other words, competence as a character trait.

The administration has e-mailed two lengthy summaries that claim "continuing progress" on the Gulf Coast. And, the other day, the Bush team flew a Katrina victim (a former local Republican candidate) up to Washington, where he lauded Bush on the South Lawn: "I wish you had another four years, man. If we had this president for another four years, I think we'd be great."

David Winston, a Republican pollster who has advised the House GOP and White House, said the other day, "Katrina clearly was not the high point for this administration, by any stretch. All levels of government took a hit, but, obviously, if you take a hit for Katrina at the national level, it's tied mostly to the Republicans, and, rightly or wrongly, people express concerns about our ability to get things done."

Nevertheless, he said, "the one general advantage we have is that the Democrats refuse to say what they would do (better). All they do is criticize. People are looking for solutions, and when Democrats don't offer any, that's a big detriment."

But, with respect to Katrina, Bush's problem is that some of his strongest critics have been people on his own side.

This past February, a 600-page report by House Republicans upbraided Bush for "a failure of leadership." Citing his Sept. 1 claim that "I don't think anybody anticipated the breach of the levees," they found that, on the contrary, many experts had repeatedly warned of a breach. The House Republicans, referring to Bush's claim, dryly observed that "comments such as those ... do not appear to be consistent with the advice and counsel one would expect to have been provided by a senior disaster professional."

By March, public perceptions had hardened. The Pew poll, since the dawn of the Bush era, has asked people, "What one word best describes your impression of George W. Bush?" No words are suggested. Twice in 2005, the most frequently invoked word was "honest." Yet in March of this year, "honest" came in sixth, a few rungs below "idiot" and "liar." The most frequently invoked word was "incompetent."

The sluggish federal recovery effort, and the bureaucratic snafus documented in recent reports, aren't likely to erase that image anytime soon.

A new study co-sponsored by the Nelson A. Rockefeller Institute of Government concluded that, because so much money has been slow to arrive or badly spent, "recovery in the struggling areas is being slowed, sometimes to a near halt." A June study by the nonpartisan General Accountability Office (an arm of Congress) found that FEMA has wasted as much as $1.4 billion, some of which was spent on champagne, football tickets and strip clubs.

It would be wrong to suggest that Bush warrants blame for everything that has gone awry in New Orleans; the U.S. Army Corps of Engineers, which had the task of protecting the city, instead spent many decades wasting money and building flimsy levees — and the Corps even admitted last April that its "design failures" played a key role in the debacle.

But Bush's critics contend that his governing philosophy compounded the tragedy; as they see it, the innate conservative hostility to big government increases the odds that power for the public good will not be wielded effectively. They cite Katrina as a classic example.

Alan Wolfe, a political analyst who directs The Boisi Center for Religion and American Public Life at Boston College, said the other day: "The public's general expectation is that Republicans from the private sector should be better than Democrats at running things. But, in reality, if you basically use government to reward your loyalists, by giving them jobs they're not qualified to have, and therefore they are not competent, then you mess things up and nothing works."

Wolfe was referring not just to Michael Brown, the Bush loyalist who got the FEMA job despite his previous experience as a lawyer for an Arabian horse organization, but also to Brown's predecessor, ex-Bush campaign aide Joseph Allbaugh, a Texan with no relief experience who gutted many FEMA programs and testified to Congress in 2001 that FEMA was just "an oversized entitlement program."

Meanwhile, Bush's current New Orleans overseer, Donald Powell, is a wealthy Texas banker with no relief experience who said last January, on the issue of aid to flooded homes, that government should not be "in the real estate business." The slow federal response recently prompted Boyd Blundell, an ethics professor at Loyola University in New Orleans, to assert that "this is what happens when you elect a government that hates government."

Kohut, the Pew pollster, said that most Americans don't view the Katrina debacle as a renunciation of conservative thinking; as he sees it, "the public is very pragmatic, and is focused on end results, not ideology." But that's precisely the GOP's problem — ineffective results. Winston, the Republican strategist, acknowledged the bottom line: "What people really want is to say, 'Just fix it. Make it work.' "

One year after Katrina, effective crisis governance is still a key challenge for the governing GOP. And with elections in November, a perceived performance deficit remains one of its greatest vulnerabilities.