Sen. 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 do n'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 ? ' Senate Appropriations Committee Ranking Democrat Barbara Mikulski , a Marylander shown in 2012 , announced that her plans for the future do n't include Congress . The diminutive Mikulski , seen standing on a box behind a Senate podium , castigated Republicans on Feb. 24 for refusing to pass a Homeland Security funding bill without a string attached that would de-fund the persident 's executive actions on immigration . 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 . Do n'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 of West Virginia and Daniel Inouye , Hawaii , both Democrats . 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 , a California Democrat , was motivated by 'emotional feeling ' when she sought an investigation of the spy agency 's harsh treatment of terrorism suspects .
Mikulski is a Maryland native who bas been in Congress since 1976 and a senator since just weeks . Democratic Reps. Chris Van Hollen and Donna Edwards , and former Govs . Martin O'Malley and Bob Ehrlich , could all run to replace her . Mikulski 's exit announcement came 1987 after a similar announcement from California Democratic Sen. Barbara Boxer .