A newly-released Associated Press poll shows President Obama leads 47 percent to 46 percent among likely voters.
But among all registered voters, the president has a 50 to 40 lead, and among all adults, he’s ahead by an even larger margin, 52 to 37 percent.
These numbers point to what might be the most important factor in determining which candidate wins this November: who actually turns out to vote. Pollsters assume, based on previous elections, nearly one third of Americans who are eligible to vote won’t. The non-voting population could reach 90 million this year.
And the majority of the non-voters would likely back the president: A USA Today/Suffolk University poll earlier this year found Obama ahead two to one among unlikely voters.
Registered voters and all adults of course include people who are almost certain not to show up, while likely voters are pollsters’ best guess at the actual electorate. (The new NBC News/Wall Street Journal poll gives Obama a five-point lead among likely voters, but all of these surveys show a tight race, and one that is closer when considering only likely voters.)
Obama is more reliant than Romney on blocs of voters who are not as consistent in turning out, particularly Latinos and adults between the ages of 18 and 29. After boosting Obama in 2008, many of them stayed home in 2010, helping Republicans win back control of the House of Representatives with strong support from people over 65, who tend to be conservative and also more consistent voters.
And it’s not completely clear the Obama voters from 2008 are coming back. A Gallup survey in June found that while 78 percent of voters overall and 76 percent of blacks said they were definitely going to vote, only 58 percent of 18-29-year-olds and 64 percent of Latinos said that of themselves.
Obama aides are aware of these demographic challenges, and it explains the prominent roles played by actors Eva Langoria and Kal Penn at the party’s convention earlier this month, as well as the constant talk about the president’s efforts to reduce college costs and make it easier for the children of undocumented workers to be granted legal status in the U.S. Those moves are designed to appeal to young and Hispanic voters, as campaign officials believe black turnout will remain high, since African-American voters remain very enthusiastic about the president.