Amanda Lucier, Associated Press
Republican presidential candidate, former Massachusetts Gov. Mitt Romney, left, introduces his vice presidential running mate, Wisconsin Rep. Paul Ryan, Saturday, Aug. 11, 2012 in Norfolk, Va. A Washington Post poll of registered voters released Sunday night gives Romney a one-point edge.

A Washington Post poll of registered voters released Sunday night gives Romney a one-point edge, with 47 to 46 percent. But digging a little into the numbers, there is reason to believe it may understate Romney's current edge.

This new poll appears even as Gallup continues to show a tie, and the Rasmussen daily tracking poll has actually edged in favor of the president. In Sunday's Rasmussen update, Obama has a 3 percent edge, right at the margin of error, and his largest lead in weeks.

The Washington Post poll of registered voters sampled 9 percent more registered Democrats than Republicans, at 31 to 22 percent. 39 percent of the sampled voters were independents.

In contrast, as Deseret News has noted before, 2008 exit polls produced a 7 point Democratic advantage, while the 2010 midterm elections were an even split. Most observers believe that 2012 will split the difference, with perhaps a 3 or 4 point Democratic advantage.

More evidence that the Washington Post sample skews in Obama's favor lies in the president's job approval rating, which in this poll stands at 50 percent. This contrasts with the most recent Gallup job approval rating of U.S. adults, which only gives the president 45 percent approval.

So the Gallup sample of U.S. adults, which is by far the most Democratic-friendly sample, as respondents do not have to be voters or even citizens, finds just 45 percent approval. But the Washington Post sample of registered voters, which should be far less Democratic-friendly, produces a 50 percent job approval for the president.

That job approval disparity, added to the D+9 sample skew, suggests the registered voter sample in the Washington Post is indeed skewed and that Romney's one-point lead in the Washington Post may be a few points higher.

Meanwhile, Obama's edge in the Rasmussen's daily tracking poll reminds us that polling is an art, not a science, and at this point no one knows for sure who has the edge in a very tight race.

Eric Schulzke writes on national politics for the Deseret News. He can be contacted at