Romney has a favorability rating of 52 percent while Obama has a favorability rating of 51 percent, results of a USA Today-Gallup poll released Tuesday indicated.
Gallup said the results indicate the candidates' favorability ratings changed little after the first debate earlier this month.
The Princeton, N.J., polling agency also said the latest poll surveyed only registered voters, not a pool of adults as previous polls had.
When considering all adults, Obama's favorability ratings generally are higher than Romney's, the poll said. In a Sept. 24-27 poll, 55 percent of all Americans had a favorable opinion of Obama and 47 percent had a favorable opinion of Romney, compared with favorable ratings of 50 percent for each candidate among registered voters in the same poll.
Results are based on nationwide telephone interviews of 891 registered voters conducted Wednesday and Thursday as part of the Gallup Daily election tracking survey. The margin of error is 4 percentage points.