The longest serving woman in the history of the United States Congress is stepping down.

Maryland Senator Barbara Mikulski, who has worked in the Capitol Hill for 38 years, has announced she is ready to retire.

Mikulski is 78 years old.

"This is a very big decision," she said, as she made her announcement in Baltimore City waterfront neighborhood at Fell's point, near her birthplace.

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This means that the Democrat senator will not anymore vye for a sixth term next year.

Mikulski cites her work for special children and getting funding for fire departments as her most important accomplishments.

She does not point to any specific period in Congress as the highlight of her legislative career.

Mikulski was elected to the House of Representatives in 1976.

She has been serving the senate since 1987.

She says she is able to draft her legislative agenda as she mingles with ordinary people, then take their mandate to Washington.

In fall of 2009, Mikulski broke her ankle, raising speculations she would not anymore seek a fifth term.

But she made a bold move, working behind a wheelchair for several months, while she was recuperating.

These days, she is the highest-ranking Democrat on the Senate Appropriations Committee.

Montana Senator John Tester, who chairs the Democratice Senatorial Campaign Committee, says, "Barbara is a force of nature on the Senate floor. She will be missed by both her colleagues and her constituents."

Mukluski has 22 more months remaining in office.

She is wondering how she should spend her remaining time in public service.

"Do I spend my time raising money, or do I spend my time raising hell?" she asks.

The Senator's exit from the Capitol Hill is set to open a new competitive Democratic primary battle in Maryland.

The contenders for her posts are Maryland representatives Donna Edwards, Chris Van Hollen, Elijah Cummings and John Delaney.

Former Maryland Democratic Governor Martin O'Malley's name has also cropped up.

TagsU.S. Congress, Barbara Mikulski, Maryland