WASHINGTON — Those in the circle of fiery House conservatives who are spearheading a fiscal showdown that threatens to shut down the government see themselves in vaunted company.

“It only takes one with passion — look at Rosa Parks, Lech Walesa, Martin Luther King,” said Representative Ted Yoho of Florida, one of the rank-and-file House Republicans who have risen up to challenge their party’s leadership over whether to confront the Senate and President Obama with their demands to cut off funding for the president’s health care law. “People with passion that speak up, they’ll have people follow them because they believe the same way, and smart leadership listens to that.”

Along with Mr. Yoho, a rotating cast of characters — often backbench newcomers whom few have heard of outside their districts, and who were elected on a Tea Party wave — has emerged to challenge Speaker John A. Boehner’s leadership at every turn.

Representative Justin Amash of Michigan, a libertarian-leaning sophomore Republican, led the revolt against the National Security Agency’s domestic surveillance programs, which Mr. Boehner had strongly endorsed. Representative Scott Rigell, Republican of Virginia, complicated his leadership’s support for the use of force in Syria when he drafted a letter demanding that the president first consult Congress.