Polls late in the week showed a 6-8 point lead for John Kerry over President Bush, but today's poll reverses that.

WASHINGTON - The Democratic National Convention boosted voters' perceptions of John Kerry's leadership on critical issues, a USA TODAY/CNN/Gallup Poll finds. But it failed to give him the expected bump in the head-to-head race against President Bush.

In the survey, taken Friday and Saturday, the Democratic ticket of Kerry and John Edwards trailed the Republican ticket of Bush and Dick Cheney 50% to 46% among likely voters, with independent candidate Ralph Nader at 2%.

Before the convention, the two were essentially tied, with Kerry at 47%, Bush at 46%.

The change in support was within the poll's margin of error of +/- 4 percentage points in the sample of 763 likely voters. But it was nonetheless a stunning result, the first time in the Gallup Poll since the 1972 Democratic convention that a candidate seemed to lose ground at his convention.