When the Maryland General Assembly opened its new four-year term today, a lobbyist for the city of Baltimore, newly hired to the post, worked his way through the statehouse crowd to the door of the Senate chamber.

He moved easily past a guard there and onto the Senate floor (a privilege normally denied to lobbyists), and with the air of an ambassador being toasted in a foreign country, planted himself confidently a few feet from the podium.

The lobbyist was former Baltimore state Sen. Harry J. McGuirk, the most powerful man in the Maryland Senate last year, a master politician who had relinquished 16 years of statehouse prestige to run for the Democratic nomination for governor.

He lost that race but today McGuirk was back, still greeted as "senator," still sporting a wavy mane of silver hair, still interviewed by reporters, and still on the Senate floor. He promised not to abuse the privilege.

McGuirk's face was not the only familiar one at the opening day festivities. A handful of former politicians, retired voluntarily or involuntarily in the last election, returned to the capitol to try out new roles. They watched from the sidelines as 66 new members spent the day having their pictures taken in high-backed leather chairs, inviting friends and family members into the normally off-limits cloakrooms, and going to an endless number of opening day parties.

While McGuirk stood on one side of the Senate podium, trying on the garb of lobbyist (joined by another former Baltimore legislator-turned-city lobbyist, James R. Dietrich), another old faithful stood on the opposite side of the chamber, savoring his final moments in office.

Former Sen. Victor L. Crawford (D-Montgomery), who gave up his seat rather than run against a well-financed challenger, pointed to his watch and told reporters, "I still have one more hour as a senator." He winced when Senate President Melvin A. Steinberg gave his old desk to Baltimore Sen. Joseph Bonvegna. "How could he do that to me?" Crawford muttered jokingly.

In the House cloakroom, talking on a private legislative phone, was former Prince George's Del. Charles Blumenthal, a gadfly during his three terms. He, too, had returned in a new capacity. He pulled a press card from his pocket that listed his news organization as "Freelance." Asked whom he was working for, Blumenthal replied, "The wife and kids."

As the celebrations continued in corridors and offices and bars, one more exiled politician, an influential and towering political figure in the state for 12 years, sat in his favorite Annapolis restaurant, sipping a drink and indulging in a plate of fresh mussels.

John Hargreaves, former chairman of the powerful House Appropriations Committee, talked about the vacation he would take in Barbados, and in Florida, and the time he would be able to spend hunting in his home territory of the Eastern Shore.

Hargreaves had floated his name unsuccessfully for a variety of appointed positions in Gov. Harry Hughes' administration.