Rep. Barney Frank (D-Mass.) said today he will retire instead of seeking a 17th term in part because Congressional redistricting left him with substantially new territory.

“This decision was precipitated by Congressional redistricting, not entirely caused by it,” Frank said at a Newton, Mass., news conference.

Frank, who said he had initially planned to retire in 2014, explained he didn’t want to be torn between introducing himself to 325,000 new constituents and representing his current district.

Frank, 71, is the ranking member on the Financial Services Committee, and the financial reform measure passed last year bears his name.

President Barack Obama praised Frank as “a fierce advocate for the people of Massachusetts and Americans everywhere who needed a voice,” comments echoed by Democratic leaders as the news reverberated on Capitol Hill.

Obama said it is thanks to Frank’s leadership that Congress passed “the most sweeping financial reform in history designed to protect consumers and prevent the kind of excessive risk-taking that led to the financial crisis from ever happening again.” The president also lauded Frank’s advocacy for gay rights.

Minority Whip Steny Hoyer (D-Md.) said in a statement that he is “saddened” by Frank’s decision and that his colleague will be “greatly missed” in Washington, D.C.

“He has brought an exceptional intellect, political courage, common sense, a wonderful wit, and a love of country and of the People’s House to his service,” Hoyer said.

State leaders lauded Frank’s years of service, with Massachusetts Democratic Party Chairman John Walsh saying in a statement that Frank “will take his place in history as a shining son of Massachusetts.”

The news comes about a month after Rep. John Olver (D-Mass.) announced his retirement and just after Gov. Deval Patrick signed the new Congressional map. The new lines significantly shifted Frank’s 4th district.

The newly drawn 4th meanders from his longtime base of support in liberal Newton and Brookline down to a portion of Fall River. It will remain a Safe Democratic seat.

Some possible Democratic candidates include City Year co-founder Alan Khazei, who recently dropped his Senate primary bid, former Brookline Board of Selectman Chairwoman Deborah Goldberg, Brookline Selectwoman Jesse Mermell, state Sen. Cynthia Creem and Bristol County District Attorney Samuel Sutter.

A Massachusetts Democratic official told Roll Call that Newton Mayor Setti Warren, who dropped out of the race for Senate, was unlikely to make a bid for Congress and instead will focus on running his city.

Walsh struck a political tone when honoring Frank.

“In 2010, Republicans made an all-out push to stem the tide of Democratic progress in Massachusetts and thanks to our better ideas, better candidates and a massive grassroots campaign that stretched from one corner of the Commonwealth to the other, that push fell short,” Walsh said in the statement. “Next year, we will mount an even bigger grassroots effort to build on the gains we made in 2010 and continue to move Massachusetts forward.”

Frank, who has been known for his acerbic wit since he came to Congress in 1981, took a dig at former Speaker Newt Gingrich (R) in discussing what he would do after he left Capitol Hill.

“Let me be very clear: I will neither be a lobbyist or an historian,” he said.