“Michele Bachmann does not have a strong record as a legislative strategist, and that’s never been her forte,” said Lawrence Jacobs, a University of Minnesota political science professor. “She says things that are kind of off the wall, but these are often calculated statements on her part, to register with conservative, grass-roots people, and that’s very hard for folks who are not grass-roots conservatives to understand,” he said. “Some of the things she says are zany and embarrassing to other Republicans, but that’s part of what has given her this authenticity.”

Ms. Bachmann’s credibility with the Tea Party movement may be her biggest asset. She often comes across as sincere, charming and cheerfully upbeat, whether she is giving a phone interview or talking about her passion for the Constitution in a cavernous ballroom, qualities that have won her many fans in the Tea Party movement.

“This is no disrespect intended to anyone on the inside of the leadership, but with Michele Bachmann, it’s like having our person on the inside,” said Tim Phillips, president of Americans for Prosperity, a conservative advocacy group. “We know she’s movement first, not party first, and we have complete confidence that when she speaks, she has our interests and the movement’s interests at heart.”

The Congressional Tea Party Caucus, which Ms. Bachmann started in July, has 53 members and is expected to increase as conservative freshmen descend on the Capitol, giving it the potential to be a crucial voting bloc. Mr. Jacobs said that Ms. Bachmann was establishing “the presence of the Tea Party Caucus as a kingmaker,” and that if she used it strategically and carefully chose a few key battles, “they can be as powerful and maybe more powerful than the Blue Dogs,” the now-depleted group of moderate and conservative Democrats who served as a counterweight to their party’s liberal wing.

When asked if the Tea Party Caucus could be a spoiler or a rainmaker for certain Republican legislation, Ms. Bachmann replied, “It could be.”

“Our focus will be on continually educating our members and practicing our craft to understand the role and the ideals of the Tea Party,” she said. “But certainly if we see leadership come forward with a bill that we believe is in opposition to Tea Party ideals, that is one vehicle where we could band together.”

For now, her plan for the caucus “is to start weekly classes on the Declaration of Independence, the Constitution and the Bill of Rights,” inviting everyone from Supreme Court justices to legal scholars to speak.

“As we’re studying every week, let’s say for instance the commerce clause, then as the legislation comes before us, we can apply through the grid of the Constitution the actual legislation that we’re looking at,” she said. “This is a tremendous real-time forum to be able to discuss these issues ahead of time, prior to the vote, in regard to principles of the Tea Party.”