“I accept the fact there are a lot of people in the country who would like us to work together,” he said. “Unfortunately, none of them appear to have either telephones or e-mail because nobody ever hears from them about specifics. When an issue comes up, anybody who’s trying to compromise only hears from the people who say, ‘Don’t give in, don’t back off.’ ”

But Mr. Frank said he was also ready to quit politics for a more pragmatic reason: he hates raising money and campaigning, and would have had to do a lot of it over the next year. That would have been an unacceptable distraction from his policy priorities, he said, like pushing for federal deficit reduction to include cuts in military spending and continuing to advocate for financial industry reform.

“The need to campaign in a district that is almost half new conflicts with that,” he said at his news conference at Newton City Hall. “If I were to run again, I would be engaged full-fledged in a campaign, which is entirely appropriate. Nobody ought to expect to get elected without a contest. But the fact that it is so new makes it harder in terms of learning about new areas, introducing myself to new people. And I have other obligations; one is to continue to serve the people I currently serve.”

Mr. Frank said he had intended to retire at the end of 2014 but had decided it would have been unfair to serve new constituents for only one term.

He said that he hoped to teach and write in the coming years, noting, “I have the longest uncompleted Ph.D. thesis in Harvard history haunting me.”

He said that being outside the halls of Congress might give him a more credible platform. “Now people just say, ‘Oh, you’re a politician, you’re just self aggrandizing, you just want to have more power,’ ” he said in the interview. “I think as a private citizen I’m less easily impugned by that.”