WASHINGTON --. President Barack Obama and Republican challenger Mitt Romney remain essentially tied in the race for the White House three days before the Nov. 6 election, according to a Reuters/Ipsos daily tracking poll released on Saturday.

Of likely voters polled nationally, 47 percent said they would back Obama, the Democratic incumbent, while 46 percent said they would back Romney, the former Massachusetts governor.

The results fall within the poll's credibility interval, a tool used to account for statistical variation in Internet-based polls.

The two men have been locked in a tight race for weeks. Both are doing final swings in battleground states over the weekend, trying to sway a small group of remaining undecided voters and to encourage their supporters to get to the polls.

The precision of the Reuters/Ipsos online polls is measured using a credibility interval, which in this case is plus or minus 3.4 percentage points for likely voters.