WASHINGTON - US President Barack Obama gained ground on Republican rival Mitt Romney in the Reuters/Ipsos daily tracking poll on Tuesday for the third straight day, leading 46 percent to 43 percent.

Released hours before the presidential contenders face off for their second debate, the poll showed the number of undecided voters had increased, indicating a drop of support for Romney among the coveted voting bloc.

The poll showed that Obama has recovered some ground from his slide after a poor showing in his first presidential debate. After dropping below Romney in the wake of the October 3 debate, Obama regained the lead on Sunday and has increased that by one percentage point each day this week.

The online survey of 1,846 likely voters was conducted between October 12 and October 16. The precision of the poll is measured using a credibility interval, which is plus or minus 2.6 percentage points for likely voters.

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