A reporter for Politico resigned Thursday after editors found descriptions, quotes and comments in seven of her articles that were similar to stories in other publications.

Reporter Kendra Marr quit after a freelance reporter for the New York Times alerted editors of the Arlington County-based publication to similarities between a Times story on transportation security and an article Marr wrote. A subsequent inquiry found additional instances in which “specific turns of phrase” in Marr’s work “bore troubling similarities” to work in other publications, according to an editor’s note posted on Politico.com on Thursday night.

People at Politico said that on Wednesday the publication began looking at Marr’s work over the past two months after hearing from the Times freelancer. They found what one journalist called a pattern of questionable practices, including using material from the Times, the Associated Press, the Hill newspaper and Scripps Howard, among others, without attribution.

Marr, 26, a former reporter for The Washington Post, was new to her beat — transportation policy — and felt “extreme pressure” to get up to speed, said a Politico colleague who spoke on the condition of anonymity.

Marr could not be reached to comment. Politico Editor John Harris referred a reporter to the publication’s public statement.

Politico has added clarifications on all of the stories that contained “improper borrowing” and inadequate attribution and linked to them on its Web site.

Politico did not give specifics about what Marr allegedly used from other publications. It posted links to her stories, which have been updated with editors’ notes saying that earlier versions drew on reporting from other publications, which were named. The notes added that “Politico regrets the omission.”

In one instance, in an article published Monday about the Transportation Security Administration, Marr wrote, “Airlines also oppose the Obama administration’s call for a new $100 per flight fee on commercial carriers and private planes, which would go to the Federal Aviation Administration for air-traffic services.”

This is similar to a Sept. 26 Times story in which reporter Susan Stellin wrote: “The airlines also oppose a provision in the administration’s proposal that would impose a new $100 per flight fee on commercial carriers and private planes, which would go to the Federal Aviation Administration for air traffic services.”

Marr is a 2007 graduate of the Medill School of Journalism at Northwestern University and won a Kaiser Family Foundation health-reporting internship with the San Jose Mercury News while still in college. She then became a reporter for The Post’s Metro and Financial sections before joining Politico. The Post is currently reviewing her work.