ABC News’ David Kerley and Mary Compton report:

The leaders in a newly released and closely watched Des Moines Register poll are the candidates who have spent the least amount of time campaigning in the state. The poll puts Herman Cain ahead of Mitt Romney, both of whom have hardly campaigned in the state, while Michele Bachmann, despite touting her Iowa roots and having won the Ames Straw Poll in August, now seems stuck in the single digits in the state.

Cain may have momentum on his side, but he has said he will cut campaign stops and interviews to avoid making mistakes he blames on exhaustion.

“My message is connecting,” Cain said today on CBS’ “Face the Nation.”  “And people are connecting with me and the specific solutions I’m putting on the table.”

And while Cain has a slight lead in Iowa, the Obama campaign already seems to be running against Mitt Romney.

“[Romney] has no core,” White House senior adviser David Plouffe said on NBC’s “Meet the Press.” “And you get the sense with Mitt Romney that, you know, if he thought it was good to say the sky was green and the grass was blue to win an election, he’d say it.”

Romney, too, has added more ammunition to recent charges of flip-flopping after he changed his position on an Ohio ballot initiative this week. He first said he had no stand on bargaining rights for Ohio government workers, but the next day said restrictions should remain in place.

“I’m sorry if I caused any confusion,” he told voters at an event in Fairfax, Va., on Wednesday.

Barring dramatic shakeups, November could claim some candidates, thinning the diverse field. Tea Party favorites Rick Perry and Bachman are in single digits in the Des Moines Register poll.

“We’re not worried about the day-to-day snapshots,” Bachmann said on ABC’s “This Week with Christiane Amanpour.” “What we’re focused on are the primary dates. And of course, everything could change by then.”

Even traditional conservatives are worried Romney may be damaging the Republican Party.

“When you are a serial reviser of your opinion, you are going to have trouble in the general election,” George Will said on ABC’s “This Week with Christiane Amanpour.” “Just ask John Kerry, who was for something before he was against something.”