MITCHELLVILLE, Md. — In the minds of most political professionals, the Democratic Senate campaign in Maryland has just entered phase two.

Phase one began right after Sen. Paul Sarbanes (D) announced in March that he’d be retiring in 2006. That’s when two veteran officeholders, Rep. Benjamin Cardin (D) and former Rep. Kweisi Mfume (D), jumped into the race.

This month, four unconventional Democrats are poised to enter the primary: Forensic psychiatrist Lise Van Susteren, real estate developer Joshua Rales, historian Allan Lichtman, and former Baltimore County Executive Dennis Rasmussen, who has spent the past 15 years as a prosperous Annapolis lobbyist. At this point, each could run an interesting campaign and be a factor in the primary outcome, but Cardin and Mfume still must be seen as the frontrunners.

But the possibility of a phase three might be most intriguing of all: Anthony Brown, the state House Majority Whip, is also contemplating joining the race.

“I believe I have the potential of putting together a statewide campaign, a campaign in pursuit of statewide office,” he said in a recent interview. “I have a sufficient amount of support.”

Brown is no ordinary state lawmaker; a 43-year-old Harvard-educated lawyer and lieutenant colonel in the Army reserves, he just returned from a nine-month stint in Baghdad. With the Maryland Democratic Party reeling from complaints that it has not done enough to promote minority candidates — and with national Democrats searching high and low for candidates who can speak with firsthand experience about the military — Brown is a very hot political property right now.

“He is, after all, a blend of the two most-discussed Democratic candidates of the past year: Barack Obama and Paul Hackett,” said state Del. Richard Madaleno (D), who began sending e-mails to Brown urging a Senate run before his colleague even returned from Iraq.

Brown’s political potency was on vivid display the other day, when dozens of Maryland politicians took time from their Labor Day weekend schedules to attend a “Welcome Home” picnic that Brown threw for himself on his street in this affluent and predominantly black suburb just outside the Capital Beltway. The red, white and blue “Welcome Home, Delegate Brown” signs appeared along the road almost two miles from his house.

Among those attending, and invited to speak to the crowd, were Cardin and the two Democratic candidates for governor, Baltimore Mayor Martin O’Malley and Montgomery County Executive Douglas Duncan.

Brown is scheduled to be fêted by more politicians and business leaders tonight, at a reception hosted by Prince George’s County Executive Jack Johnson (D).

The conventional wisdom says that O’Malley and Duncan would both welcome Brown onto their tickets as the candidate for lieutenant governor; Brown is also, in addition to a Senate run, contemplating a bid for state attorney general. Should he choose to seek re-election in 2006, he is seen as a leading candidate for Speaker of the state House, whenever that post becomes available.

“I think Anthony’s ticket can be punched at any station he chooses to board the train on,” said George Owings, a former legislator who is Maryland secretary of Veterans Affairs. “He’s well-liked and he knows what he’s doing.”

Asked if that includes the possibility of a Senate run next year, Owings said, “I don’t think that’s out of the question. If you’re asking this time, it may be a little premature. But he definitely has an unlimited future.”

If anything prevents Brown from making the Senate race, it may be his current position — and the notion that he isn’t quite ready for prime time yet.

“Don’t talk about running for the U.S. Senate,” said one veteran Democratic operative in Maryland. “You sound silly, coming from the House of Delegates.”

“I think it’s a little presumptuous to say, ‘Hey, Obama did it, why can’t I do it?’” said another party strategist. “Anthony Brown’s name recognition is probably next to zero even in Prince George’s County.”

But after seven years in the Legislature and experience running local campaigns in Prince George’s County, Brown is more politically seasoned than most of the newcomers to the Senate race. And he clearly has more star power.

“His stock is never going to be higher now on a statewide basis,” Madaleno said. “Why run for lieutenant governor or attorney general?”

Brown said he will explore his political options and see “what makes sense.”

“My concern truly is that the Democratic Party field a good ticket, a diverse ticket, a balanced ticket,” he said.

Despite the loyalty of Maryland’s black voters to the Democratic Party, it was Republicans who elected Maryland’s first statewide black official, Lt. Gov. Michael Steele. And Steele is almost certain to be the GOP nominee for Senate next year — a fact that puts pressure on Democrats to find a high-profile black candidate for the 2006 ballot.

In the growing Democratic field for the Senate seat, Mfume is the lone black candidate, but party strategists have been disappointed with his campaign to this point. Brown is beginning to catch the attention of national Democratic leaders, party operatives said.

All these factors may make a Senate run seem very tempting.

“The larger the field is, the less likely it is that there is a shoo-in,” Brown said.