More voters will watch Wednesday’s debate than perhaps any other campaign event until Election Day, but a Washington Post-ABC News poll released this week finds one critical group of voters may skip out on the prime time face-off: Persuadable voters.

Just 32 percent of voters who say they are undecided between President Obama and Mitt Romney or could still change their mind are “very interested” in the presidential debates. By contrast, 53 percent of “definite” Romney voters and 59 percent of resolute Obama supporters are “very interested.”

The poll's finding underscores the challenge for Obama and Romney to sway a shrinking and elusive slice of the electorate with less than five weeks left in the contest. In addition to lacking clear support for Obama or Romney, on-the-fence voters are much less likely to say they are “absolutely certain to vote” than those with firm opinions, even further limiting their potential impact on the election.