Updated 11:36 p.m. ET
One of Rep. Michele Bachmann's top political advisers is reducing his role in her presidential campaign in what appears to be a shakeup as the Minnesota congresswoman struggles to maintain her momentum.
Ed Rollins, a respected veteran of many Republican presidential campaigns -- including the late president Ronald Reagan's -- is stepping down from his day-to-day duties for what he and the campaign say are health reasons. He'll become a senior adviser. Rollins' deputy, David Polyansky, is leaving the campaign.
In a statement released late Monday, the Bachmann campaign announced it is "executing a planned restructuring strategy," likely in response to the entrance into the presidential race of Gov. Rick Perry, a candidate who appeals to the same populist, socially conservative constituency as Bachmann and who already has a national fundraising network.
Since Perry entered the race, he has rocketed to the top of the polls while Bachmann's once meteoric rise has halted.
Perry's entrance into the race "has slowed our money down," Rollins acknowledged on CNN's AC360 program Monday night, where he phoned in to discuss his changed role. "It took a lot of the momentum that we could have gotten out of the straw poll victory," he added, referring to Bachmann's victory in a symbolically important balloting of Iowa Republicans last month.
Of Bachmann, he said: "I think she is the third candidate at this point in time." But he added that Perry has yet "to prove himself" and that Bachmann "is a good debater." Rollins emphasized that he is remaining with the campaign. But at 64 and having survived a stroke, "I just don't have the endurance to do 12-14 hour days, seven days a week anymore," he said.
Bachmann spokeswoman Alice Stewart said that the campaign's strategist, Keith Nahigian, will become interim campaign manager "as part of the restructuring strategy."
"Keith has played a vital role in the success we have had to date and I'm confident he can lead us to a strong finish in Iowa, New Hampshire, South Carolina and across the country," Bachmann said in a statement issued by her campaign.
Longtime Bachmann aide Doug Sachtleben dismissed speculation that Bachmann's husband, Marcus, would be taking a key role in the campaign.
"No, that would not happen. I can tell you that with certainty. Michele loves Marcus and trusts him dearly as her spouse of almost 33 years, but he would not take a position of leadership in the campaign."
Bachmann's hiring of Rollins in June gave immediate credibility to the three-term congresswoman's campaign. The veteran strategist helped engineer former Arkansas Gov. Mike Huckabee's surprise win in the 2008 Iowa caucuses, and was central in her victory in this year's Iowa Straw Poll. "I am grateful for his guidance and leadership and fortunate to retain his valuable advice," the congresswoman said in the statement her campaign released.
Stewart, who was hired by Rollins, told a reporter for National Journal and CBS that she will be staying with the campaign.
Sarah Huisenga contributed to this report.