U.S. Sen. Barbara Mikulski (D-Md.) delivers remarks during a news conference on the government shutdown and its effects on the National Institutes of Health in 2013. (Shawn Thew/European Pressphoto Agency)

Sen. Barbara A. Mikulski’s retirement announcement has created a new round of turmoil for Maryland Democrats, exposing divisions within their party as it recovers from losing the governor’s mansion to the Republicans last November.

Within days of Mikulski’s surprise announcement last week, at least nine prominent Democrats signaled interest in the seat. The field includes most of the state’s congressional delegation, two former lieutenant governors and a mayor.

About the only top Maryland politician to count himself out was Martin O’Malley, the former Democratic governor who is busy exploring a campaign for the White House.

“What you have is everyone looking in the mirror and saying, ‘I’m the one,’ ” said Gloria Lawlah, a former Maryland state senator and now the chairwoman of 1000 Maryland Women, a political action committee. “There will have to be something to distinguish someone and propel them to the top.”

Maryland’s status as a solidly Democratic state is one reason for the intense interest in Mikulski’s seat. But a bitter primary could weaken the party and the eventual nominee, drawing a robust Republican challenge in a state where the GOP wants to build on Gov. Larry Hogan’s win last year.

Rep. Chris Van Hollen (D-Md.) speaks at an American Federation of Government Employees rally on Capitol Hill in Washington on Feb. 10. (Andrew Harnik/For The Washington Post)

On the Republican side, former Gov. Robert L. Ehrlich, former lieutenant governor Michael S. Steele, Rep. Andy Harris and Dan Bongino, a former Secret Service agent who nearly won a congressional seat in November, are among those who have told associates they are interested in running.

The early jockeying has exposed fissures in the Democratic Party. Rep. Chris Van Hollen is the only Democrat formally to have announced his candidacy. But liberal activists quickly launched a draft movement to propel Rep. Donna F. Edwards into the race.

As he announced his candidacy, Van Hollen took steps to establish himself as the front-runner, brandishing endorsements from two prominent Maryland Democrats, Attorney General Brian E. Frosh and Montgomery County Executive Isiah Leggett.

On Friday, Van Hollen received the blessing of Senate Minority Leader Harry M. Reid (D-Nev.). But Reid’s endorsement — announced just ahead of the 50th anniversary of the “Bloody Sunday” civil rights march in Selma, Ala. — prompted Steve Phillips, a Democratic donor and the founder of a political action committee, to accuse Reid on Twitter of being “insulting” to “Blk folks and women (Donna Edwards).”

At the same time, the draft Edwards movement was announced by two nationally recognized progressive groups, Democracy for America — founded by former Vermont governor Howard Dean (D) — and the Progressive Change Campaign Committee.

With Maryland’s high concentration of black voters, Mikulski’s retirement is an opening for an African American to win a statewide seat and enter a political body that has had only seven black members since Reconstruction.

Blacks accounted for roughly 43 percent of voters in last year’s Democratic primary in Maryland, according to a Washington Post poll — a rate likely to rise in the race to succeed Mikulski because it will occur alongside the presidential election.

But with a handful of established black Democrats considering the race — including Edwards, Rep. Elijah E. Cummings, former lieutenant governor Anthony G. Brown, Baltimore Mayor Stephanie Rawlings-Blake and Benjamin T. Jealous, former head of the NAACP — the quest for another African American U.S. senator may be undermined if the black vote is divided.

But multiple white Democratic candidates seeking the seat also could fracture the electorate. In addition to Van Hollen and Rep. C.A. Dutch Ruppersberger, Reps. John Delaney and John Sarbanes — all white — have expressed interest in the seat.

Similarly, more than one female candidate — Edwards, Rawlings-Blake, Heather R. Mizeur, a former state delegate who ran for governor last year, and former lieutenant governor Kathleen Kennedy Townsend, who also is considering the race — could divide female voters.

“Any ethnic group would like to have their base to themselves and not split with another person,” said Larry Gibson, a Baltimore-based political consultant. “That will be the case, white and black.”

Gibson said the pool of potential candidates will shrink as the race unfolds and aspirants test their viability through polling and fundraising. In addition, a number of the potential candidates, particularly those in Congress, may choose to forgo the risk of losing their seats.

“The field won’t be nearly as large as it is now,” Gibson said. “This is an uncertain step. That’s going to weed out a lot of people.”

No kingmaker

Mikulski’s retirement announcement unleashed a torrent of pent-up ambition in a state in which elected leaders tend to occupy seats for what can seem a political eternity.

Mikulski was elected in 1986, taking her seat in 1987. Until his 2007 retirement, Paul S. Sarbanes (D) had been in the U.S. Senate for 30 years. Rep. Steny H. Hoyer, whose district includes southern Maryland and chunks of Prince George’s and Anne Arundel counties, has served in the House since 1981. In Annapolis, Thomas V. “Mike” Miller Jr. has been president of the state Senate since 1987.

Depending on who from the state’s congressional delegation seeks Mikulski’s seat, another wave of competition could occur for at least one U.S. House seat.

State Del. Dereck E. Davis (D-Prince George’s) became giddy talking about the falling dominoes.

“A year from now, this could be unlike anything we’ve ever seen,” he said. “You just don’t usually have the potential for change in one fell swoop. We’re usually much more stable.”

And no one is kingmaker.

With Hogan’s stunning defeat of Brown, and with no Democratic governor for the first time in eight years, Maryland Democrats lack the kind of leadership that can bring order to the jumble of potential candidates. “There are no bosses in here anymore, and there’s no machine,” Lawlah said. “A machine would have cleared the field. Some of those names would never see paper.”

In Annapolis, state lawmakers puzzled over the field as they received calls from potential contenders seeking support. State Sen. Nathaniel J. McFadden (D-Baltimore), who has heard from Van Hollen and Cummings, said choosing a candidate would be difficult.

“There are too many options,” he said. “That’s why you have to be deliberative in the process.”

McFadden, who is African American, said he hopes a black candidate becomes senator, because “it’s time.” But he also expressed admiration for the white potential contenders, including Van Hollen, with whom he worked when the congressman served in the state Senate. Sarbanes, he said, “has been an outstanding leader,” while Delaney’s centrist approach may be more effective in a state that chose a Republican governor.

“We in Maryland need to pay close attention to that,” McFadden said.

Handicapping the field

Among the potential candidates, Van Hollen’s stature is considerable. A close ally of House Minority Leader Nancy Pelosi (D-Calif.), who hopes to convince him to remain in Congress, Van Hollen’s base of support is in Montgomery County, which has a history of turning out the most voters. He also has proved that he can raise money, and has $1.7 million in his campaign account.

Edwards, too, has impressed Democrats since arriving in Congress in 2008 after defeating powerful incumbent Rep. Albert R. Wynn (D).

Her Prince George’s County base, with its active population of African American voters, would be a strength. But Edwards also has support among white voters, with her alliances with women’s and progressive groups.

“Van Hollen starts out as the most formidable contender,” said Ron Lester, a veteran pollster. “But Donna has potential. She is a tenacious campaigner. She is popular among black voters. But she’s also popular among whites. She is the quintessential crossover candidate.”

While Edwards has declared publicly that she’s well-suited to succeed Mikulski, Cummings, a former prosecutor with a commanding voice, has been more circumspect. His district includes parts of Baltimore City, and Baltimore and Howard counties. He, too, has support among whites and blacks.

Cummings also is a key House member, serving as the ranking Democrat on the Committee on Oversight and Government Reform, and on the panel investigating the bombing of the U.S. diplomatic compound in Benghazi, Libya.

“There will be a lot of pressure on Cummings to stay in place,” Lester said. “He plays a very critical role.”

Brown’s potential candidacy elicited little enthusiasm among several Democratic Party operatives, who said his losing gubernatorial campaign was a weak foundation for another race.