CEDAR FALLS, Iowa (AP) - Feeling optimistic, Republican presidential candidate Mitt Romney on Thursday was positive on TV with an upbeat, new ad but in person went negative against President Barack Obama.

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He also announced an aggressive schedule of campaign events for the days leading up to next week's caucuses. Romney, who is wrapping up a bus tour of eastern Iowa on Friday, planned to campaign in New Hampshire early Saturday before returning to Iowa that evening for a series of events on the economy.

Those events are to be followed by six campaign rallies, mostly in eastern Iowa, from Sunday through Tuesday's caucuses, including an early morning one before voters start gathering to declare their candidate preferences.

Meanwhile, vowing to press ahead through the Iowa caucuses, Republican Michele Bachmann dismissed the notion Thursday that her presidential campaign was in disarray.

Her comments came a day after a key supporter fled her campaign and she had to fend off other calls to leave the race for the GOP nomination.

The Minnesota congresswoman called her campaign organization "strong" and said her headquarters had received 150 calls of support after her Iowa campaign chairman, state Sen. Kent Sorenson, resigned and switched his allegiance to rival Ron Paul. Sorenson backed Paul on Wednesday, a few hours after appearing with Bachmann.

She alleges he was offered "a lot of money" to change sides, an inducement she said Sorenson had told her about during a telephone conversation on Tuesday. "I know what I was told in that conversation," Bachmann said.

The Paul campaign and Sorenson deny that money factored into the decision or that any such offer was made. Sorenson told CNN on Thursday that he wanted to back a candidate who is in a position to keep Mitt Romney from winning Iowa.

"It's unfortunate they're resorting to these type of tactics," Sorenson said. "But the fact of the matter is she wasn't going to win Iowa."

Bachmann's Iowa political director, Wes Enos, said he doesn't believe Sorenson left for money. Enos said he was staying with the Bachmann campaign.