en. Barbara Mikulski, the longest serving woman in the history of Congress, announced Monday that she will not run for-re-election.

“‘Do I spend my time raising money, or do I spend my time raising hell?'” the 78-year-old old Maryland Democrat, now in her fifth term, said she asked herself when deliberating whether to seek a sixth term next year.

“I don’t want to spend my time campaigning for me. I want to campaign for the people,” she said at a news conference in the Fells Point neighborhood of Baltimore. “Do I spend my time promising what I would do — or do it now and do it the way I like to?”

Mikulski, a tough, no-nonsense lawmaker who rose to the leadership of the powerful Appropriations Committee, became the longest-serving woman in the history of Congress in 2012. She was first elected to the House of Representatives in 1976 and has served in the Senate since 1987.

She said that when her term has ended, “I will know that I will have given it my best shot.”

Her retirement is certain to set off a race among potential candidates to succeed her, including Democratic Reps. Chris Van Hollen and Donna Edwards, and former Govs. Martin O’Malley, who is considering a bid for the Democratic presidential nomination, and Republican Bob Ehrlich.

She becomes the second Senate Democratic woman to announce her retirement this year, following Barbara Boxer of California.

In a 2014 interview, Mikulski said her approach as chair of the Appropriations panel was “to focus with civility and courtesy. Old school values. Don’t do surprises or stunts and negotiate directly and not through the press.” In her state, she has been fiercely protective of the environment, especially Chesapeake Bay issues.

Senate Republican Leader Mitch McConnell described Mikulski at the time as forceful and results-oriented. “I think she’s terrific,” he said.

Mikulski had been seen as more engaging and approachable than her predecessors as appropriations chairman, the late Sens. Robert C. Byrd, D-W.Va., and Daniel Inouye, D-Hawaii. She had spent decades honing relationships with members of both parties, learning their needs and end goals.

After a short tenure as chairman, she now is the top Democrat on the panel after Republicans captured control of the Senate in last November’s elections.

“She knows that if you know somebody and what they want, you can help them be successful. And when you help people be successful, Republicans or Democrats, that’s how you move bills,” said Democratic Sen. Patty Murray of Washington, a Mikulski protege.

Mikulski has also been an active advocate of equal pay for women. The Maryland senator sponsored legislation last year aimed at tightening a 1963 law that made it illegal to pay women less than men for comparable jobs because of their gender. But Senate Republicans blocked the bill in an April 2014 floor showdown.

“When I hear all these phony reasons, some are mean and some are meaningless, I do get emotional,” Mikulski said of arguments against the legislation. “I get angry. I get outraged. I get volcanic.”

Mikulski played off former CIA Director Michael Hayden’s recent comment that Senate Intelligence Committee Chairwoman Dianne Feinstein, D-Calif., was motivated by “emotional feeling” when she sought an investigation of the spy agency’s harsh treatment of terrorism suspects.

via Veteran Democratic Sen. Mikulski Won’t Seek Re-Election – ABC News.