UPDATE 3:45 p.m. EST: Sen. Barbara Mikulski, the longest-serving woman in Congress, Monday announced she will not seek a sixth term in the U.S. Senate. Mikulski, 78, told a Baltimore news conference she is eager to help the next generation of Democrats take over, the Baltimore Sun reported.

"Do I spend my time raising money or raising hell to meet your day-to-day needs? Do I spend time focusing on my election or the next generation?" Mikulski, D-Md., said. "The more I thought about it, the more the answer became really clear.

"That's why I'm here to announce I won't be seeking a sixth term as a United States senator for Maryland," she said.

Mikulski began her congressional career in the House in 1976.

Original post:

U.S. Sen. Barbara Mikulski, D-Md., the longest-serving woman in the Senate, announced Monday that she will be retiring from the body and will not seek a sixth term in 2016, according to multiple media reports. Mikulski, 78, was expected to formally announce her retirement at an 11 a.m. news conference, the Baltimore Sun reported.

Maryland’s senior senator is the vice chairwoman of the Senate Appropriations Committee, which is the committee responsible for allocating funds to federal agencies. In this role, Mikulski is a prominent figure in the fight over funding the Department of Homeland Security, which Republicans have taken aim at over President Barack Obama’s executive actions on immigration. On Friday, shortly before Congress voted on a one-week extension for DHS funding that doesn’t settle the debate, she accused Republicans of “having a temper tantrum with the president of the United States over his executive authority.”

“Don’t punish the border control agent. Don’t punish the person working in the Coast Guard out on an ice cutter. Don’t punish the volunteer firefighter because you’re angry at Obama,” Mikulski said from the Senate floor.

Among Mikulski’s notable votes in the Senate was her vote against the resolution authorizing military force in Iraq in 2002. Mikulski was one of 23 senators to vote against the war. She also voted against the resolution that authorized the Gulf War in 1991. That war was approved by a vote of 52-47 in the Senate.

Known for her ability to gain bipartisan support for legislation, Mikulski has been called the “dean” of female members of the Senate, according to CNN. In her speech on the Senate floor Friday, she said she had “nothing but great respect for” U.S. Rep. Hal Rogers, R-Ky., with whom she worked to get full DHS funding in last year’s “cromnibus” legislation, but the measure failed.

It’s unclear how much the impasse over DHS funding played a role in Mikulski’s decision to retire.

In a more lighthearted moment from the Senate floor, Mikulski elicited chuckles during an Appropriations Committee hearing in June 2013 when she stopped the hearing to respond to a tweet from BuzzFeed reporter Susie Gray. Watch the video below: