Former Maryland governor Martin O'Malley speaks with reporters after addressing a conference hosted by the South Carolina Democratic Party last weekend. (Bruce Smith/AP)

Former Maryland governor Martin O’Malley said Tuesday that he will not run for the U.S. Senate seat being vacated in 2016 by retiring Sen. Barbara A. Mikulski, removing one well-known name from a long and growing list of possible replacements.

The decision, announced less than a day after Mikulski (D) said she would step down, is the latest indication that O’Malley is serious about pursuing a long-shot White House bid.

O’Malley has said he will decide by spring whether to launch a Democratic primary campaign that would probably pit him against Hillary Rodham Clinton. After a trip to South Carolina on Saturday, he is headed to Democratic Party events in New Hampshire this weekend and will travel to Iowa later this month.

“I think this makes it pretty clear that he’s going to run for president or at least give it a shot,” said Thomas F. Schaller, a political science professor at the University of Maryland Baltimore County.

Jockeying among others who may be interested in the Senate seat continued Tuesday, with seven of the state’s eight House members signaling interest — everyone except for Democratic Whip Steny H. Hoyer, 75.

Rep. Donna F. Edwards (D) sounded like a candidate as she told reporters about the parallels between Mikulski’s career and her own, promising to “make a decision in the coming days.”

“She has never lost sight of the fact that she was a social worker,” Edwards, who has worked as a community advocate, said of ­Mikulski. “I share a lot of that, because part of the way that I came into Congress was very, very similar.”

Edwards, who was elected in 2008, said “it makes sense” for her to consider a Senate run, “and that’s what I’m doing. I’m going to try to be smart about it and thoughtful about it.”

Rep. John Delaney (D) announced Monday on Twitter that he would explore a bid. Aides to the others — Republican Andy Harris and Democrats C.A. Dutch Ruppersberger, Elijah E. Cummings and Chris Van Hollen — said their bosses are also considering the option. Van Hollen’s aide said he was “very likely” to run.

Baltimore Mayor Stephanie Rawlings-Blake (D), who is up for reelection in 2016, will make a decision within a few weeks, a spokesman said Tuesday.

Republican Dan Bongino, who challenged Delaney last year and was the GOP’s Senate nominee in 2012, tweeted Tuesday: “Big news coming tomorrow. Stay tuned. #mdpolitics.”

In Annapolis, state lawmakers gossiped about which congressional seats might come open as people entered the Senate race and who would compete for them.

While several members of the General Assembly coyly declined to reveal their plans, Sen. Jamie B. Raskin (D-Montgomery) said he was considering running for Van Hollen’s seat if Van Hollen runs for Senate.

“I am strongly exploring it,” Raskin said. “There’s a statewide game of musical chairs going on right now.”

Raskin, who described himself as a pragmatic progressive, was elected to the Maryland Senate in 2006 and played a role in passing legislation on same-sex marriage, repealing the death penalty and increasing penalties for drunk drivers.

“I would like to bring an effective progressive agenda to Washington if the culture of Capitol Hill is not too dysfunctional,” he said.

Most Montgomery County Council members deflected questions Tuesday about interest in Van Hollen’s seat, saying they would wait for his announcement. But that didn’t quiet speculation. “It’ll be an orgy,” said council member Marc Elrich (D-At Large).

One reason the race will be attractive is that it falls between council elections, so incumbents don’t have to give up their seats to run. Even losing can be a win, because a good showing puts a candidate in line for other opportunities — such as the county executive’s race in 2018.

Among the names being mentioned are Council President George L. Leventhal (D-At Large), council member Hans Riemer (D-At Large), council member Craig Rice (D-Upcounty) and council member Roger Berliner (D-Potomac-Bethesda).

Bill Turque and Paul Kane contributed to this report.