This week, their relationship changed. Bachmann's new strategist, Ed Rollins, harshly criticized Palin, describing her as "not serious," and what was once a natural alliance has turned into a potential rivalry.
The collision may have been inevitable. Bachmann and Palin appeal to the same stripe of the electorate and are strikingly similar in style and ideology.
"Maybe there is only room for one articulate, good-looking conservative broad in the race," Minnesota GOP strategist Sarah Janacek said. "We ain't come that far, baby, I'll tell you that."
Bachmann's camp has distanced itself from Rollins' comments, but the hard feelings have set in. A Palin aide publicly asked for an apology. Others, including Fox News talker Greta Van Susteren, are calling on Bachmann to dump Rollins -- hired only this week -- before she formally announces her candidacy later this month.
"Is this how Representative Bachmann wants to start her campaign ... with a guy ... that makes her look petty?" Van Susteren blogged this week. Van Susteren, whose husband served as a Palin adviser in the 2008 presidential campaign, noted that Palin was helping the Minnesota Republican's U.S. House re-election campaign when she appeared with Bachmann last year in Minneapolis.
The contretemps between Bachmann and Palin intensifies the suspense about whether the former Alaska governor will enter the 2012 race, where she could be expected to claim many of the same activists who have come out for Bachmann.
Some have detected a sexist tinge in the Washington punditry, as on Wednesday, when a CNN guest referred to the growing Bachmann-Palin rivalry as "the catfight of the century."
"There are white men who look very similar to one another who are also competing for the same voters, and we're not seeing the same type of stories," University of Minnesota political scientist Kathryn Pearson said. "So gender has something to do with this."
Bachmann aides did not respond to a request for comment about the blowback on Rollins' remarks. But Bachmann's congressional spokesman, Doug Sachtleben, issued a statement saying that "the two enjoy a good friendship" and that Bachmann "has nothing but admiration and respect for Governor Palin."
Rollins, who ran President Reagan's re-election campaign in 1984, started the row on Tuesday, the day after telling the media he would run the Bachmann campaign.
As for Palin, Rollins told Fox News Radio host Brian Kilmeade, "Sarah not been serious over the last couple of years," adding, "she got the vice presidential thing handed to her. She didn't go to work in the sense of trying to gain more substance. She gave up her governorship."
Hours later, Bachmann aide Andy Parrish, who had yet to confirm Rollins' role in the Bachmann campaign, emailed the Star Tribune: "The congresswoman and Ms. Palin have an excellent relationship. Rollins was in his media analyst role."
Nevertheless, Palin aide Michael Glassner fired back at Rollins the next day: "Beltway political strategist Ed Rollins has a long, long track record of taking high profile jobs and promptly sticking his foot in his mouth," Glassner said in a statement. "... One would expect that his woodshed moment is coming and that a retraction will be issued soon."
Instead, Rollins told Politico that while he "missed a step" in his transition from analyst to political strategist, he takes nothing back.
Phone and email messages left with Rollins' public policy firm this week have not been returned.
Bachmann insiders have long speculated privately that Palin will not enter the GOP nominating contest, leaving open the possibility that many of her ardent Tea Party supporters could be up for grabs.
But Rollins' statements came as Palin's national bus tour is sparking speculation that she may jump in the race after all.
Bachmann's role in forming a Tea Party caucus in Congress has been a double-edged sword. "She's looked at as more part of the establishment than Palin," said Toni Backdahl, a Tea Party activist from Plymouth. "Instead of participating with grass-roots people, she had her marketing people start their own Tea Parties."
Pearson and others recognize Rollins could have been sending a signal to elite party donors and opinion leaders, contrasting Palin's pop culture image with Bachmann's credentials as a tax attorney, Tea Party leader and three-term member of Congress.
Hamline University political scientist David Schultz said he sees Rollins' move as an effort to differentiate Bachmann and delegitimize Palin.
"Most of us are thinking of Palin and Bachmann as competing for the same Tea Party, social conservative, far-right of the party," he said. "Bachmann has to convince people in that part of the party, 'Don't put your eggs in Palin's basket.'"