By CHARLES BABINGTON and THOMAS BEAUMONT
WASHNGTON - Mitt Romney chugged ahead Thursday as the conservative-fueled drive to deny him the Republican presidential nomination reached a difficult new phase: Once-surging rivals Rick Perry and Herman Cain scrambled to control serious damage, while an old face sought new ways to exploit their problems.
Former House Speaker Newt Gingrich could emerge as the newest hope for conservative activists who doubt Romney's commitment to their priorities. But Gingrich trails Romney and others in organizing in key states such as Iowa. And he will have to prove that his long and sometimes troubled political history can withstand closer scrutiny.
Meanwhile, Texas Gov. Perry rearranged his schedule Thursday to try to mitigate a disastrous debate moment, in which he could not remember the third federal agency he has vowed to abolish. Perry canceled a Tennessee fundraiser to appear on several TV networks and the David Letterman show, pledging to stay in the race.
He repeatedly said he "stepped in it" at the Wednesday night debate but declared in an interview, "This ain't a day for quitting nothing."
For Cain, the former pizza company executive, it was day 11 of trying to get beyond sexual harassment accusations leveled against him by four women, two of whom received cash settlements from a trade association Cain once headed.
Facing voters for the first time since the allegations emerged, Cain met with tea party groups in Michigan, hoping the friendly settings would preserve the lofty perch he enjoyed in GOP polls two weeks ago.
"How you beat Obama? Beat him with a Cain!" he told one supporter at a crowded diner in Ypsilanti. The crowd cheered.
He is airing his first TV ad in Iowa, and he has hired a new lawyer who is warning women they will be scrutinized for any charges made against the candidate.
Romney, the former Massachusetts governor who recently filmed a TV ad in Iowa, blasted President Barack Obama's Iran policy in a Wall Street Journal opinion piece Thursday. His supporters quietly reveled in the good fortune of Perry's and Cain's woes.
With the Iowa caucus set for Jan. 3, and the New Hampshire primary a week after that, Romney is looking strong, but he's hardly home free. Many conservatives still resent his past support of legalized abortion and gay rights, and his requirement that all Massachusetts residents obtain health insurance.
But they have failed to coalesce around a single alternative. Rep. Michele Bachmann briefly topped the polls, followed by Perry and then Cain. It's unclear whether Cain can hold his position.
Some Iowa Republicans hope former Pennsylvania Sen. Rick Santorum, who emphasizes social conservative issues such as abortion and gay rights, can make a move. He has visited all 99 Iowa counties and aired radio commercials.
Other party insiders feel the person best poised to rise is Gingrich, the fiery Georgian who led the GOP's 1994 takeover of the House (after 40 years in the minority). He eventually lost his leadership post and left the House after clashing with President Bill Clinton over taxes and an unpopular government showdown.
Gingrich is adding staff in key states, opening new offices this week and raising more money than he has in months.
With Romney widely seen as the front-runner in New Hampshire, a rival must do well in Iowa to surpass him. Gingrich is popular with many Iowa Republicans, and he drew good reviews for his speech at a large dinner in Des Moines last week.
But he has little structure in place for the organizationally intensive caucuses, which require people to show up for gatherings on a mid-winter night. Gingrich has not done much of the retail-level campaigning seen by past successful caucus candidates. His schedule in the next 10 days shows him visiting the state to promote a movie he produced with his wife and participate in a multi-candidate event aimed at social conservative activists
Gingrich has had no paid staff in Iowa since a mass exodus of his campaign team in June. He plans to name a staff and open campaign headquarters in Iowa soon,
"What I'm seeing now is a real surge of energy" for Gingrich, said supporter Linda Upmeyer, Iowa's House majority leader. "The bright, shiny things have come and gone, and now people are focusing on a decision."
A key question is whether Romney will see Cain's and Perry's problems as a chance to make a big push in Iowa. A win there would make him the prohibitive favorite. But to fare poorly after raising expectations would echo his disappointing Iowa performance four years ago.
Romney has made only four public visits to Iowa this year. But a small core of advisers and staff keeps in close touch with key elements of the Iowa network he assembled in 2007.
Romney has phoned activists and held multiple question-and-answer conference calls that included thousands of potential voters. He has been the most consistent poll leader in Iowa without pulling away. The Des Moines Register's late-October survey showed Romney with 22 percent, narrowly trailing Cain.
Romney has a healthy contingent of precinct-level caucus leaders, an edge over many of his rivals. He has sponsored phone calls criticizing Perry's position on immigration.
However, Romney has avoided multicandidate forums in Iowa. He is not expected to participate in an event sponsored by a social conservative group in Des Moines on Nov. 19, or the evening fundraiser for Iowa Gov. Terry Branstad the same evening. Several other candidates are expected at both events.
Bachmann had a bumpy day Thursday. About 30 Occupy Wall Street protesters loudly interrupted her foreign policy speech in Mount Pleasant, S.C., saying she was dividing the nation. Bachmann left the stage but returned and finished her speech after the protesters departed.
Associated Press writers Kasie Hunt in Michigan, Shannon McCaffrey in Atlanta, Bruce Smith in South Carolina and Phil Elliott and Steve Peoples in Washington contributed to this report. Beaumont reported from Iowa.