Attorney General Douglas F. Gansler. (Photo by Bill O'Leary/The Washington Post)

Antigone Davis, a longtime aide to Attorney General Douglas F. Gansler (D), has taken over as the campaign manager of his Democratic gubernatorial bid, Gansler told supporters in a letter distributed Friday.

Davis is the third aide to hold the title since this summer. She replaces Matthew “Mudcat” Arnold, a Democratic operative who came on board in July after a brief stint by Carrie Glenn, who left because of a health condition that interfered with the job, according to the Gansler campaign.

Both Arnold and Glenn had worked on campaigns for Democratic candidates and liberal causes around the country. Davis, by contrast, has been one of Gansler’s closest confidants in Maryland for years, leading his 2006 and 2010 campaigns for attorney general and serving as a senior adviser in his government office.

“Antigone knows campaigns; she understands government; and she knows Maryland,” Gansler said in the letter, which confirmed rumors that had been circulating in recent weeks about a staff shake-up. “I feel lucky to have her serve as day-to-day campaign manager.”

In an interview, Gansler said that Arnold had played a key role in the formal launch of his campaign in September but that he is confident that he now has “the best operation going forward.”

“We’ve got the team we believe is the best in the state, if not the country,” Gansler said.

Arnold has “done a terrific job and will remain a valued consultant through the end of the year,” he said in his letter.

Arnold is a veteran of Democratic congressional campaigns in Texas, Ohio and Washington state, and he managed a liberal super PAC in 2012 that targeted tea party Republican members of Congress. He had also worked for the Sierra Club and and as a principal in a Washington-based consulting firm.

Gansler’s letter also noted several other hires, including veteran political strategist and media consultant Jay Marlin as a senior adviser a month ago. Marlin has done work for the campaigns of presidents Obama and Bill Clinton and has had senior roles in statewide and congressional races in states such as Connecticut, Ohio and North Carolina.

In recent weeks, Gansler said, his campaign staff has added a policy consultant, press secretary and research director, as well as a political aide for his running mate, Del. Jolene Ivey (D-Prince George’s).

Gansler faces Lt. Gov. Anthony G. Brown and Del. Heather R. Mizeur (Montgomery) in June’s competitive Democratic primary.

After a debut that was marred by some unflattering news stories, Gansler has sought in recent months to regain his footing. He has cast himself as an Annapolis outsider armed with plenty of policy ideas. He has also been hammering Brown for his role in the state’s troubled rollout of its online health insurance exchange.

“With this strong campaign team, Jolene and I will continue to run a campaign focused on building a stronger Maryland for everyone — by improving Maryland’s economy, closing the achievement gap in our schools, addressing income inequality and improving the lives of hard-working families,” Gansler said in the letter.