There remains almost no daylight between President Obama and Republican Mitt Romney as the 2012 presidential campaign nears its conclusion, according to the latest Washington Post-ABC News tracking poll.

Likely voters nationally continue to divide about down the middle: 49 percent support Obama, 48 percent back Romney. It’s the 10th consecutive release with the two contenders both at either 49 or 48 percent. The poll’s margin of sampling error is plus or minus 2.5 percentage points.

While the election officially concludes Tuesday -- barring administrative problems and recounts -- the voting is already over for more than a quarter of all voters. Nationally, 27 percent of likely voters say they have already cast their ballot in the contest; in the eight key “toss-up” states, early voting rates spike higher to 35 percent.

Voters in these eight states have received outsized attention. Fully 38 percent of all likely voters in these states say they have personally heard from the Obama campaign in just the past week; as many, 37 percent, say they have heard from Romney’s side.

A split verdict on Obama’s job performance still undergirds the tightly competitive contest: 50 percent approve of the way he is handling the presidency, and 49 percent disapprove. But Obama does carry some advantages into the election.

The president has a 10 percentage-point lead over Romney when it comes to whom voters trust more to handle an unexpected crisis. Obama also has twin, six-point leads as the “stronger leader” and the one who is more in touch with the economic problems people in the country are having.

Another, potential important edge for Obama is on enthusiasm. With just two days to go, 69 percent of his supporters call themselves “very enthusiastic,” compared with 62 percent of Romney’s. Enthusiasm for both candidates has increased sharply over the course of the campaign.

Romney counters with a very slight edge in voters’ trust to handle the economy, 49 to 46 percent.

The two candidates also are closely matched on which one has the “better ideas about the right size and role of the federal government:” on this score, 48 percent of likely voters side with Romney and 45 percent with Obama. Numbers on this question are virtually identical to where they were three weeks ago, well before Hurricane Sandy and its aftermath reignited debate about federal responsibilities.

Obama had clear vulnerabilities on the “big government” question, which Romney may have missed. In July, voters seeing Obama’s views about government as a major reason to oppose him outnumbered those who saw it as a big reason to support him. And in August, most voters said they were out-of-sync with Obama on the matter: a clear majority said they themselves preferred “smaller government with fewer services,” but more than three-quarters said Obama wants a “larger government with more services.”

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 Oct. 31 to Nov. 3, among a random sample of 2,069 likely voters. The margin of sampling error for the full four-night average is plus or minus 2.5 percentage points.

Crosstabs from the tracking poll are available at this link. And comparisons to the 2008 exit poll are available here.

The final release of the Post-ABC tracking poll will be 5 p.m. Monday.