Think most voters have already made up their mind this year? Not so fast.

An ABC New/Washington Post poll finds that up to 25% of voters may still be persuadable this year. The survey says 29% of voters who are leaning toward Mitt Romney and 24% of those leaning toward Barack Obama may be persuadable.

Why? It comes down to anxiety.

53 percent of Obama’s backers say that regardless of their supporting him, they’re anxious about how he’d perform in a second term as president – and even more of Romney’s supporters, 62 percent, are anxious about their man. Four in 10 overall also say they’re interested in more information about the candidates. And 25 percent meet both those conditions: anxious about their candidate, and looking for more information.

There are some differences among groups. Age is one, with senior voters least apt to be persuadable -18 percent of those older than 65 are persuadable, compared with 28 percent of adults 18 to 64. There’s also a regional effect, with persuadability higher in the Midwest (31 percent) and lowest in the Northeast (18 percent).

Attitudinal measures are particularly interesting. Moderates and “somewhat” conservatives are more apt to be persuadable than liberals or “very” conservatives (29 vs. 21 percent), evidence that less ideologically committed voters are more persuadable ones. In another example, persuadability is higher among people who are either somewhat opposed to the Tea Party movement, or somewhat supportive of it, compared with “strong” supporters or opponents.