WASHINGTON — President Bush has a double-digit lead in one new national poll, but he's tied with Democrat John Kerry in another.

Both campaigns say their own polling has the race close, with Bush's people seeing a slight lead for the president.

Kerry and Bush are tied in a Pew Research Center poll taken Sept. 11-14, after Bush was up by 12 points or more from a Pew sample taken Sept. 8-10. A Gallup poll being released early Friday has Bush up 54 percent to 40 in a three-way matchup, with Ralph Nader at 3 percent.

"After so long when the polls were deadlocked no matter what happened, now we have a situation where voter opinion is unsettled," said Andrew Kohut, director of the Pew Research Center for the People & the Press. "There's a lot of uncertainty, and you're going to have more variation in the polls than we've had in the past."

The first of two national polls by Pew, done Sept. 8-10, reflected the president's post-convention bounce. Bush was ahead of Kerry 52-40 among registered voters and by an even wider margin, 54-39, among likely voters, a narrower group.

By the second poll, done Sept. 11-14, the Bush lead had evaporated, the center said Thursday. In that poll, Bush and Kerry were knotted at 46 percent among registered voters. Among likely voters, Bush was at 47 percent and Kerry at 46 percent.

While Bush has held onto some positive impact from the GOP convention, his "vulnerabilities on Iraq and the economy continue, and these have anchored the race," Kohut said.

After the Republican convention and its four days of criticism of Kerry, Bush grabbed a lead ranging from 5 points to 11 points in various national polls. That lead appeared to be shrinking by late last week, and a Harris poll out Thursday also showed the race even.

Bush continues to hold a commanding lead on the question of who would do the best job of defending the country from terrorists, by 58 percent to 31 percent in the Pew poll. And he's seen by more as a strong leader.

But people are more likely to disapprove of Bush's handling of the economy and are evenly split on his dealing with Iraq. Almost six in 10 said it's not clear what Bush will do about Iraq if he is re-elected.

Interest in the presidential debates is high with 61 percent saying it's very likely they will tune in to watch — compared with 43 percent who said that in September 2000. Three in 10 said the debates will matter in their voting decision.

By a 3-1 margin, voters said they think Bush is likely to win re-election in November.

The first Pew poll of 970 registered voters was taken Sept. 8-10 and the second poll of 1,002 registered voters was taken Sept. 11-14. The margin of sampling error for both polls was 3.5 percentage points.

The Gallup poll of 767 likely voters was taken Sept. 13-15 and has a margin of sampling error of plus or minus 4 percentage points.