WASHINGTON — They're the most fickle voters, and potentially the most powerful. Thus, with party nominations secure, John McCain and Barack Obama now are pushing toward the center to win them over.

Meet the "mushy middle," a complex chunk of voters likely to decide the presidential election but difficult to reach and hard to please.

They aren't uniformly conservative or liberal, and they don't fit strict Republican or Democratic orthodoxy.

"To me, it's not about the party, it's about who is the best person for the job," says Pam Robinett, 47, of Wellington, Kan., who always votes. Then again, "they'll all lie, cheat and steal to get what they want."

Talk about a tough sell.

"The country's going to go to hell in a handbasket with this election," seethes James Nauman, 55, from Lutz, Fla. "I don't think Obama's qualified and McCain's another Bush. Neither of them really have impressed me."

A recent AP-Yahoo News poll finds that 15 percent call themselves moderates and aren't solidly supporting a candidate. More than half of this still-persuadable middle is made up of independents.

The survey, conducted by Knowledge Networks, found that three in four Republicans and three in four conservatives are backing McCain, while Obama has nearly identical support among Democrats and liberals.

Some 39 percent of voters called themselves Democratic, 29 percent Republican, and 32 percent independent in the June 13-23 survey. (The overall margin of sampling error was plus or minus 2.3 percentage points.)

Still, the likeliest path to the White House cuts through the center of the electorate.

"They're the kingmakers in American politics," said Matt Bennett, a Democratic operative at the centrist Third Way policy group. "They're the people who decide elections."

Who exactly are these power-wielding voters?

A significant majority of them have a low opinion of Bush and Congress. They have more favorable impressions of Democrats than Republicans. Many are feeling the economic pinch. They want troops to return from Iraq as soon as possible.

Like the broad electorate, they rank gas prices and the economy as their top concerns, followed by health care, Social Security, taxes and education. Terrorism and Iraq are lower.

Compared with far-right and far-left voters, this group tends to be more Hispanic, more Catholic than the left, and more secular than the right. They are more likely to be married with children and live in far-flung suburbs or rural areas. They also tend to be less educated.

Nearly half view McCain favorably, while slightly more than a third see Obama positively. Still, the candidates are little-known to a quarter of them, and many have little enthusiasm for either.

This voting group's views cross some of the usual lines.

For instance, they overwhelmingly favor abortion rights and legal rights for same-sex couples, typically Democratic and liberal positions. But they also overwhelmingly say cutting taxes should be a high priority, typically a Republican and conservative refrain.