WASHINGTON — To the conservative Americans she courted, Maria Butina was the right kind of Russian.

She loved guns and the church and networking with top officials in the National Rifle Association. She schmoozed with Republican presidential candidates, and became a supporter of Donald J. Trump. She spent Thanksgiving at a congressman’s country house, took a Trump campaign aide to see the rock band Styx and helped a Rockefeller heir organize “friendship dinners” with influential Washingtonians.

On Thursday, Ms. Butina, 30, pleaded guilty to a single charge of conspiring to act as a foreign agent in a deal with federal prosecutors. In doing so, she acknowledged that her activities were motivated by more than mere personal conviction.

As part of the deal, Ms. Butina admitted to being involved in an organized effort, backed by Russian officials, to open up unofficial lines of communication with influential Americans in the N.R.A. and in the Republican Party, and to win them over to the idea of Russia as a friend, not a foe.

Ms. Butina’s guilty plea now casts a spotlight on the Americans she worked with, including prominent members of the N.R.A. and her boyfriend, Paul Erickson, 56, a longtime Republican operative who ran Patrick J. Buchanan’s 1992 presidential campaign and who now faces accusations of fraud in three states. Officials have said federal investigators are examining what Mr. Erickson and others who helped Ms. Butina knew about her links to the Russian government.