The presidential primary season has been good for Democrats and tough on President Bush, according to a national poll released Thursday.

The survey by the Pew Research Center (search) for the People & the Press found that the public's impression of the Democratic field has been improving as the candidates have battled for their party's nomination — with 45 percent now viewing the field positively, compared to 31 percent a month earlier. Bush's overall favorability rating, meanwhile, still is positive at 53 percent, but that compares with 72 percent last April, shortly after the fall of Baghdad, and is the low point of his presidency.

Likewise, Bush's job-approval rating has dropped to 48 percent, the first time in his presidency that it has fallen below 50 percent, according to the poll.

"I'm a little surprised by how negative people are toward Bush personally," said Andrew Kohut (search), director of the Pew poll. He said the negative views of Bush might be linked to the high number of people who are paying attention to the failed hunt for weapons of mass destruction in Iraq. Three-fourths of Americans say they are following the issue very or fairly closely.

When the pollsters asked people for a one-word description of Bush, equal shares gave positive and negative responses, a stark shift from last May, when positive answers outnumbered negative ones 2-to-1. The most frequently used negative word this time was "liar," which never came up last May. The most frequently used positive description this time was "honest," the same as last May.

The shifting perceptions of Bush and the Democrats have been accompanied by changing expectations for the outcome of the general election this fall — 51 percent now think Bush will win, compared with 61 percent a month earlier. Among Democrats, 25 percent now think Bush will win, compared with 38 percent in January.

Kohut said Republicans didn't enjoy a similar boost in 1996, the last time there was a contested primary to determine who would take on an incumbent president, Bill Clinton.

"When Bob Dole seemed likely to be the nominee, there wasn't this big bounce for him," Kohut said. "This has been a surprise how much attention the public's paid and how favorably they've responded to the Democrats generally."

Public impressions of the leading Democratic candidates this time are generally positive. Two-thirds of those who are familiar with front-runner John Kerry have a favorable view of him. John Edwards, Kerry's closest challenger, has a 63 percent favorable rating among the smaller group of people who are familiar with him.

Kohut said Democrats shouldn't be "deluded" about their candidates' strength.

"Kerry's support is less an endorsement of his candidacy than a reflection of opposition to Bush," the pollsters wrote. "Fully twice as many Kerry supporters characterize their choice as a vote against Bush rather than a vote for Kerry."

Asked for a one-word description of Kerry, 78 percent of voters were able to offer a response. Some 38 percent gave a positive answer, such as "honest," "good" or "qualified,' and 19 percent gave a negative response, such as "phony," "arrogant" or "liar."

The Pew survey of 1,500 Americans was conducted Feb. 11-16 and had a margin of error of plus or minus 3 percentage points.