How Kevin McCarthy Forged an Ironclad Bond With Marjorie Taylor Greene

“That conversation had a big impact on me,” she said.

From then on, the two settled into a kind of symbiotic relationship, both feeding off what the other could provide. Ms. Greene began regularly visiting Mr. McCarthy, frequently dropping by his office, and he began inviting her to high-level policy discussions attended by senior Republicans and praising her contributions.

He was impressed not only by Ms. Greene’s seemingly innate understanding of the impulses of the party’s hard-right voters, but also by her prowess at building her own brand. He once remarked to allies with wonder at how Ms. Greene, as a freshman, was already known by a three-letter monogram: M.T.G. “She knows what she’s doing,” Mr. McCarthy marveled privately. “You’ve got A.O.C. and M.T.G.”

After Republicans underperformed expectations in the midterm elections, winning only a narrow majority and guaranteeing that Mr. McCarthy would have a tough fight to become speaker, Ms. Greene was quick to begin barnstorming the right-wing media circuit as one of his top surrogates, using her conservative credentials to vouch for his.

As her peers on the far-right flank of the party refused to support Mr. McCarthy, subjecting the Republican leader to a four-day stretch of defeats, Ms. Greene was unflinching in her support, personally whipping votes on the House floor and strategizing on calls with Mr. Trump.

Ms. Greene’s support for Mr. McCarthy created a permission structure for other G.O.P. lawmakers to do the same.

Representative Barry Moore, Republican of Alabama, said in an interview that when conservatives back home sought an explanation for his support for Mr. McCarthy, he would comfort them by replying: “Well, Jim Jordan and Marjorie Taylor Greene are standing with Kevin McCarthy. And so am I.”

The relationship has also paid off for Ms. Greene, no longer the fringe backbencher stripped of her power. Republican leaders announced last week that she would serve on two high-profile committees: Oversight and Homeland Security. She is also likely to be appointed to a new Oversight select subcommittee to investigate the coronavirus, according to a source familiar with Mr. McCarthy’s thinking who was not authorized to preview decisions that have yet to be finalized.