Sen. Barbara Mikulski (D-Md.) says she will support giving President Obama the authorization to launch airstrikes against the Syrian government, providing the administration a key backer from a wing of the Democratic Party that has been hesitant to get on board.

Mikulski is the longest-serving woman in congressional history. As the chairwoman of the Senate Appropriations Committee, a member of the Senate Intelligence Committee and an ardent Obama administration supporter on most issues, her voice carries weight.

“I believe the president’s plan is the best response to protect U.S. security interests in the region. ... I will support the president’s request for a targeted, limited military action,” Mikulski said on the Senate floor Monday. “Let me be clear: I have no grand hopes or illusion about what this strike will do … but I do believe that it will deter and degrade [Syrian President Bashar al-Assad’s] capacity to strike again.”

Mikulski’s move brings to 24 the number of senators who say they support authorizing strikes, while 28 are against or leaning against and 48 are undecided, according to The Washington Post’s running tally.

Like many lawmakers from both parties, Mikulski has mostly heard from constituents that they are opposed to a strike.

“My constituents have spoken loud and clear,” she said. “They don’t want a war. They don’t want boots on the ground. … They don’t want war and neither do I. Yet the use of chemical weapons … mandates a response,” Mikulski said.

Mikulski has been skeptical of past U.S. military initiatives. She voted against authorizing the Persian Gulf War in 1991, and opposed invading Iraq in 2002. In the latter case, she recalled Monday, she had real doubts about Bush administration intelligence purporting to show that Iraq had weapons of mass destruction.

“This time is different because I truly believe, after extensive briefings … I am satisfied that indeed chemical weapons were used in Syria, and I am satisfied that the Assad regime gave the order to do so.”

If the U.S. does not strike, Mikulski said, “I fear that Assad, Iran and North Korea will be further emboldened.” She added that she had “listened to the president’s promise and I take him at his word that any action would not be boots on the ground … that we’re not in it to do regime change.”

Until Monday, Mikulski had been publicly undecided on the wisdom of striking Syria.

“I think that what we heard today made a compelling forensic case: One, that nerve gas was used and No. 2, that it was used by the Assad regime,” Mikulski told reporters after a classified briefing last week. “The next step has to be, then, what is the way to both deter and degrade his ability to ever do it again? I have more questions about that. Does a military strike do that?”