Romney had a 3 percentage point lead -- still within the margin of error -- among likely voters last week, but that lead was 1 percentage point Monday, 48 percent to 47 percent, results of the UPI-CVoter poll indicated.
Five percent of registered voters said they were undecided with with 15 days until Election Day.
Polling was conducted before and after the second presidential debate Tuesday. Obama was thought to have won that debate and Romney was considered to have won the first debate Oct. 3.
The latest UPI survey also indicated 50 percent of registered voters said they approved of the president's first-term performance and 45 percent said disapproved.
Results indicated 38 percent of registered voters said they believe Republicans are better positioned than Democrats to tackle the problems facing the country, a figure unchanged from the previous week. Thirty-two percent said they believe Democrats would do a better job, up from 30 percent last week.
Results are based on nationwide telephone interviews Oct. 15-21 with 1,316 registered voters of which 1,151 said they were likely to vote in the Nov. 6 election. The overall margin of error is 3.5 percent and 4.5 percent for the sample of likely voters.