Republican John McCain and Democrat Barack Obama are dead even in two opinion polls as they head into the final eight weeks of the election campaign for the White House.
The polls were taken between Friday and Sunday after last week's Republican convention.
A CNN/Time poll showed the race deadlocked at 48%, and a Hotline/Diageo poll put the two candidates even at 44%.
The CNN/Time poll was largely unchanged from the previous week, when Mr Obama led Mr McCain by 49% to 48%.
The Hotline poll showed a significant convention rebound for Mr McCain, who trailed Mr Obama by 9 percentage points in a poll taken the week before.
Another poll released on Sunday, by USA Today/Gallup, gave Mr McCain a 4-point edge among registered voters and a 10-point lead among likely voters. Mr McCain trailed Mr Obama by 3 points among likely voters in the week before the Democratic convention.
Some polls also showed Mr McCain has boosted the enthusiasm level among his supporters with the choice of Alaska Governor Sarah Palin as his running mate.
The CNN/Time poll of 1022 Americans was taken by Opinion Research Corporation and had a margin of error of 3%. The Hotline/Diageo poll of 924 voters had a margin of error of 3.2%.
The election is on 4 November.