Updated 2:48 p.m. | There is a long list of candidates who might run to replace Sen. Barbara A. Mikulski, who announced Monday she would not seek another term.

The Democrat’s exit opens a Senate seat in Maryland for just the second time since 1986, when Mikulski was elected. The floodgates are now open for the lengthy catalog of ambitious politicians in the state, which includes much of the House delegation but extends well beyond that.

Maryland has traditionally been a solidly Democratic state, and Democratic sources said House Minority Whip Steny Hoyer may be the only Democrat in the delegation not expected to consider it:

• Rep. Chris Van Hollen . He is popular with progressives, has a large national profile and fundraising base, and represents Montgomery County — one of the most important sources of votes for a candidate seeking statewide office. The Democrat is also a member of House leadership with the potential to rise further up the ranks in the future, so a Senate bid isn’t necessarily a foregone conclusion. Van Hollen would start with a strong war chest. He ended 2014 with $1.7 million in cash on hand.
• Rep. John Delaney. As the third richest member of Congress as of 2013, Delaney would certainly have the monetary resources to mount a bid. He raised $2.6 million for a competitive race in 2014 and ended the year with $25,000 in cash on hand. In a tweet Monday afternoon, Delaney said he “will explore a race for Senate.”
• Rep. Donna Edwards. The question, sources said, is whether she can raise the money. Edwards raised just $576,000 in the 2014 cycle, and has just $30,000 in her campaign war chest.
• Rep. Elijah E. Cummings. He would be another top tier candidate. His home base of Baltimore could provide a geographical advantage in a crowded primary with multiple candidates from the D.C. suburbs of Prince George’s and Montgomery counties. Cummings had $891,000 in his campaign account as of the end of 2014. He raised $899,000 in the 2014 cycle.
• Rep. John Sarbanes. He has the golden last name as the son of former Sen. Paul Sarbanes, who held Maryland’s other Senate seat for 30 years, until retiring in 2006. He raised $776,000 in the 2014 cycle and had $748,000 in cash on hand at the end of 2014.
• Rep. C.A. Dutch Ruppersberger. Sources said the 69-year-old would also likely consider the seat.

If any or all of those candidates ran, it could have a huge domino effect in state politics. The House members would have to forgo re-election to run for the Senate, creating ripples down the ballot.

The open seat could also be a fortuitous opportunity for former Gov. Martin O’Malley. He has openly mulled a presidential bid for the past several years, but his chances look increasingly poor in the face of the juggernaut that is Hillary Rodham Clinton’s campaign-in-waiting. He remains popular with the Democratic base in Maryland, and running for the Senate could give him a graceful exit from the presidential sphere, while still keeping him in the political scene. O’Malley’s mother, incidentally, is Mikulski’s longtime secretary.

Another national figure that Maryland Democrats are eyeing: U.S. Labor Secretary Thomas E. Perez. He is a former member of the Montgomery County Council and still lives in Maryland. Perez would be a highly formidable candidate, Maryland Democrats said, because he has a strong fundraising base and his political positions are attractive to Democratic activists. His position also affords him a large amount of media attention and time in front of a camera, which would be helpful in a crowded Democratic race.

Several Democratic sources also mentioned Heather Mizeur, a former member of the Maryland House of Delegates who ran for governor in the Democratic primary in 2014. She lost, but she ran a strong campaign and has a following within the Democratic Party.

Democrats also mentioned Baltimore Mayor Stephanie Rawlings-Blake, Baltimore County Executive Kevin Kamenetz, and Prince George’s County Executive Rushern L. Baker, III.

Another possible contender is Peter Franchot, the state comptroller. Franchot was Democrats’ largest vote-getter in 2014, winning re-election with 63 percent of the vote in a year when Democrats did poorly statewide. A well-placed source said the comptroller does not have interest in seeking the seat. Franchot could be a force in the race no matter what, if he chooses to endorse.

In a state where Democrats have historically prevailed, the Republican bench is much smaller. Rep. Andy Harris, the lone Republican in the congressional delegation, is expected to float his name, but GOP sources said he is unlikely to actually run.

Former Gov. Bob Ehrlich would be a top recruit. Ehrlich has said he is considering a long-shot bid for president, so he could be amenable to seeking a different federal office. Also on the list: newly elected Lt. Gov. Boyd Rutherford; Kendel Ehrlich, the former Maryland first lady; and Kathy Szeliga, the minority whip in the Maryland General Assembly.

Dan Bongino, a former Secret Service agent, could add his name to the list. He did not rule out a bid in a statement posted on Facebook Monday. Anne Arundel County Executive Steve Schuh and Howard County Executive Allan Kittleman could also run, though both won elections in 2014, so it would be soon for them to consider another office.

Related:

Barbara Mikulski Announces Retirement

Russ Feingold, Joe Sestak and the Improbable Senate Rematch

The 114th: CQ Roll Call’s Guide to the New Congress

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