The race simply could not be any closer. New Gallup, Rasumussen and Fox News polls earlier this week show Mitt Romney and Barack Obama tied at 46 percent each.
There is a lot of noise in these polls, and each of them arrived at its destination through different routes.
As of Wednesday morning, Obama was up 3 points in the Rasmussen poll
The Gallup poll has been especially volatile, showing three lead changes in April alone. This includes two successive weeks in mid-April when first Romney and then Obama held leads outside the margin of error.
The Rasmussen survey has been more stable over that period, showing Romney generally holding a lead near the margin of error.
In addition to differences in how they got here, the polls differ considerably in who they sample. Gallup and Fox News both sample registered voters, while Rasmussen filters and samples only likely voters. A registered voter survey normally will favor Democrats, whose supporters generally turn out in lower percentages at the polls.
Even further down the food chain is the "all adults" sample, taken by the National Journal on April 22, that showed Obama leading by eight points.
Most experts agree that April polls are relatively meaningless, as the voters have not yet begun to think seriously about the choices. As Nate Silver at the New York Times notes, "The leader in national polls at the end of April in the past two elections has gone on to win. Before 2004, however, the April leader lost the popular vote more often than not."
Eric Schulzke writes on national politics for the Deseret News. He can be contacted at firstname.lastname@example.org.