NEWTON, Mass. — Rep. Barney Frank, D-Mass., a gay pioneer in Congress and a liberal whose name as well as fingerprints are on last year’s sweeping bill regulating Wall Street, announced plans Monday to retire at the end of his current term.

“There are other things I would like to do with my life,” Frank said at a news conference. He said his retirement after 16 terms in Congress was hastened by two years of reapportionment, which moved 325,000 new constituents into his district.

Frank’s career has traced an arc from early promise to near career-wrecking scandal to legislative triumph, accompanied by a quick-witted intelligence and a frequently acerbic speaking style.

In Congress, Frank, 71, has fought for years to hold down what he viewed as excessive military spending, and said one of his objectives for his final year in office is to make sure the Pentagon shares in any deficit-cutting measures that take place.

Two years after a voluntary 1987 disclosure that he is gay, Frank had to explain why he had hired as a personal aide a convicted drug user and male prostitute, Steve Gobie, who also was living in the lawmaker’s apartment. Frank said he always paid the aide out of personal funds, but the House ethics committee recommended Frank be censured for using his congressional status on behalf of the man, including seeking dismissal of 33 parking tickets.

Some Republicans sought a harsher punishment, including expulsion, but majority Democrats blocked the move, and Frank resumed a career that far outlasted many of those who had sought his ouster.

Frank is the 17th Democrat to announce he will not seek re-election in 2012, when Democrats face an uphill battle to gain the 25 seats they need to win a majority in the House. By contrast, six Republicans are retiring.