Heading into Election Day, likely voters divide 50 percent for President Obama and 47 percent for his challenger, Republican Mitt Romney, according to the latest, final weekend release of the Washington Post-ABC News tracking poll.

A nail-biter throughout, the presidential contest remains closely competitive through its last days, even as most voters perceive a likely win for the president.

In regular polls since early July, neither candidate ever gathered more than 50 percent of likely voters, and neither ever slipped below 46 percent. Across nearly 7,000 interviews with likely voters from Oct. 18 through Sunday evening, less than four-tenths of a percentage point separates Obama and Romney.

The difference between the candidates in the final weekend tally is right at the 2.5 percentage margin of sampling error for the final four-night sample of 2,345 likely voters. This makes Obama’s being at plus three points over Romney an edge only by the slimmest of margins, well below conventional measures of statistical significance.

Still, hitting 50 percent is a first for Obama since the poll in early July, with Sunday interviews marking Obama’s single best day of the tracking poll. Just over 10 days ago, the tracking poll see-sawed in Romney’s direction by the same, slender 50 to 47 percent.

It is clearer that the president made progress in other areas. He has re-gained an advantage when it comes to understanding the economic problems people are having in the country, and, over the final week, has drawn back to running evenly with Romney in voter trust to handle job No. 1: the economy.

Obama has also closed the gap among white voters, inching back above the 40 percent threshold some analysts see as critical to his reelection. In the final days, white voters divide 56 percent for Romney, 41 percent for Obama. More than three-quarters of non-whites, 76 percent, back Obama, 20 percent side with Romney.

The president has also neutralized Romney’s previously large advantage among political independents. Independents divide 48 percent for Romney to 46 percent for Obama; Romney’s advantage had peaked at 58 to 38 percent 10 days ago.

The Post-ABC tracking poll is a series of consecutive one-night “waves” of interviews reported as a rolling, multi-night average. The new results are for interviews conducted Nov. 1-4.

For the entire tracking poll, a total of 9,397 randomly selected adults were interviewed by telephone (conventional landline and cellphone) over the course of 18 days, including 8,098 registered voters and 6,818 likely voters. Sampling, data collection and tabulation by Abt-SRBI of New York.

Crosstabs from the final weekend release of the tracking poll are available at this link. Comparisons to the 2008 exit poll are available here.

The table below shows results from select groups across the combined 18 waves of the tracking poll.