Analysts see little risk in the candidates making such attacks central to their pitches in a state noted for its antipathy to the president. But there may be risk in not doing more.

Pollster John Zogby said “it is extremely safe” for the candidates to attack Bush when they are gathered in San Diego. “But,” he added, “it's also not enough.”

“They have to present an alternative. Bashing Bush is not enough. They are already going to get from that what they're going to get. This time, they have to appeal to the center,” he said. “What a Democrat has to understand is they are not really running against George W. Bush. They are running against the party of George W. Bush. And presumably the nominee is going to present a new Republican face.”

In that context, it is worth noting that while liberal voters are likely to dominate the state's Feb. 5 Democratic presidential primary, the party is allowing independents to vote. The state Republican Party has refused to open its primary to nonaligned voters.

Stuart Rothenberg, the Washington-based editor of a respected nonpartisan newsletter, said the president's unpopularity has defined the 2008 race.

“The president affects the tone and the rhetoric of the Democratic race,” he said. “He's an easy mark. He is easily demonized. Whether it is John Edwards or Hillary Clinton or Barack Obama or Joe Biden, they have to take shots at the president.”

But Rothenberg said it is important to the independent voters who will decide the next election just how those attacks are couched.

“You don't have to be so bile-filled and so nasty that you look petty,” he said, adding, “I think they also have to show they have their own substance and their own experience and talk more positively about their own agendas.”

Rothenberg said Democrats only have to study the 2004 campaign of Howard Dean to understand what happens to a candidacy when it is fueled only by hostility to Bush.

“You need a certain bearing and a certain stature and a certain seriousness,” he said. “Look at what happened to Howard Dean. He was all about beating the crap out of Bush. . . . But if that's the only thing, it is hard to be presidential and be on the attack 24/7.”

But some Democrats suggest piling on Bush won't hurt the candidates at the San Diego convention.

“The Democrats running for president have a lot of leeway,” said veteran California Democratic operative Garry South. “Bush's popularity right now in California is about the same as President (Mahmoud) Ahmadinejad of Iran, maybe lower. You couldn't trash Bush enough in California.”

Indeed, the latest polls indicate Bush's standing in the state is historically low. In a survey taken April 13-15 for three television stations including KGTV in San Diego, only 9 percent of the state's Democrats approved of the job the president is doing. In the Field Poll taken March 20-31, just 10 percent of California Democrats approved of Bush.

South notes Bush twice lost California by double digits.

Meanwhile, there is pressure on the candidates to keep up their attacks on the president as studies are showing that the new contributors from the Internet tend to be more liberal and more anti-Bush than are the more traditional contributors.

But South said another object lesson in focusing on attacks came last year when Phil Angelides, the Democratic gubernatorial nominee, lost to Republican Gov. Arnold Schwarzenegger even though Democrats across the country were winning big. South, who worked against Angelides in the Democratic primary, said Angelides lost in part because he based too much of his campaign on attacks against Schwarzenegger and spent too little time showing he could get things done in Sacramento.

He said the Democratic candidates also must understand their audience is more than just the activists at the convention.

“It doesn't take a rocket scientist to understand that in this day of mass media when you give a public speech you're not really talking to the people in that room,” he said. “You have to understand that you're talking to a larger audience.”

The Democrats' task is easy, of course, compared to the impact of the president's unpopularity on the Republican candidates fighting for the GOP nomination.

“Their situation is dire,” said South, likening it to what Democrats faced in 1968 when Hubert Humphrey tried to succeed an unpopular Democratic president presiding over an unpopular war. “Humphrey came close, but he couldn't in the end split the difference between total repudiation of a very unpopular and discredited president under whom he served and going in his own direction in a way that did not alienate Democratic voters.”

Rothenberg said Republican candidates are saddled with Bush and “really can't criticize him” without losing support among core GOP voters. “It's the old problem of not wanting to be defined by Bush but not being prepared to take him on head-on. . . . You usually don't ingratiate yourself with your party by attacking your party leader.”

That dilemma is one of the reasons why Democrats enter this convention so enthusiastic about their 2008 chances and buoyed by their first-quarter fundraising reports.

“Those numbers are astonishing,” South said. “To have the Democratic presidential candidates . . . out-raise the Republican field $80 million to $50 million is unheard of.”