The Pew Research Centre and Harris Interactive found the bounce that the recent Republican convention gave the Bush campaign is fading while support for the Democratic contender is rebounding.
"Some of the negative attacks against Kerry are wearing off and he has stayed in the game because people are discontent with Bush on Iraq and the economy," said Andrew Kohut, director of the Pew Research Centre for People and the Press.
The new surveys followed two other polls in recent days, by Investor's Business Daily and a Democratic group, Democracy Corps, that found the race essentially even again, just as it was for months before the Republicans and the Democrats held their conventions.
Other polls also showed Bush, who had taken a double-digit lead after the Republican convention, slipping ground.
John Kerry has sharpened his
attack on President Bush
"Unfortunately for Kerry, he has been unable to tap into that unhappiness, especially on Iraq," Kohut said, noting Bush still beats Kerry 52-40 % on who was favoured to lead the war in Iraq.
"It's a mixed picture for Kerry, but that's better than what he had a few days ago".
A New National Annenberg Election Survey earlier this week found Bush gaining ground as a leader and in the war on terror, but his approval ratings among undecided and persuadable voters dropped below levels prior to the Republican convention.
Kerry has sharpened his message and gone on the offensive against Bush on Iraq and economy, challenging the president's credibility and his leadership on both issues.
The Pew survey sampled voters in two phases. In the first phase taken between 8-10 September, Bush had a 16-point lead over Kerry. But in the second phase between 11-14 September, the lead had been reduced to an insignificant one point.
The Harris poll also showcased an upswing in Kerry's fortunes. In its poll conducted between 9-13 September, he had a one-point lead over Bush.
In the June poll, it was Bush who had a 10-point lead over Kerry.