Gannett News Service

Last week's Democratic convention boosted voters' impressions of John Kerry but failed to give him the expected bump in the head-to-head race against President Bush, a USA TODAY/CNN/Gallup Poll finds.

In the survey, taken Friday and Saturday, Bush led Kerry 50 percent to 46 percent among likely voters. Independent candidate Ralph Nader was at 2 percent.

The survey showed Kerry losing 1 percentage point and Bush gaining 4 percentage points from a poll taken the week before the Boston convention.

The change in support was within the poll's margin of error of plus or minus 4 percentage points in the sample of 763 likely voters. But it was nonetheless surprising, the first time since the chaotic Democratic convention in 1972 that a candidate hasn't gained ground during his convention.

A Newsweek poll taken Thursday and Friday gave the Democratic ticket a 49 percent to 42 percent lead. Over three weeks, that reflected a 4-point ''bounce'' for Kerry, the smallest ever in the Newsweek poll.

Among registered voters in the USA TODAY poll, Kerry and Bush each had 47 percent. Bush was up 4 points, Kerry unchanged from the pre-convention survey.

Analysts said the lack of a bounce may reflect the intensely polarized contest. Nearly nine of 10 voters say their minds are made up and won't change.

''The convention, typically a kicking-off point for a party, is now merely a reaffirmation'' of where voters stand, said David Moore, senior editor of the Gallup Poll.