They're not calling it the Thomas V. Mike Miller Jr. Senate Office Annex--not yet. But the expansion of the home of the Maryland General Assembly, now underway in Annapolis, has the look of a monument to the Senate president, the Prince George's County Democrat from Clinton.

The planned four-story office building, scheduled to be completed in November 2000, will have a large first-floor office suite for the Senate president, including a conference room, staff offices and a private bathroom. Miller, who has held the Senate presidency for 16 years, almost certainly will be the first occupant of those offices.

There will be similar quarters on the second and third floors for the chairmen and vice chairmen of the Senate's four major committees, according to floor plans made available by Miller's office.

The $20 million annex also will have more comfortable quarters for residents and lobbyists attending legislative hearings. The blueprints show four new hearing rooms that will seat 90 people each, almost double the capacity of the chambers in the James Senate Office Building.

Built more than 60 years ago, the James building has long since been outgrown by the institution it houses. The building, on Bladen Street between Calvert Street and College Avenue, now houses 46 senators in cramped, old-fashioned quarters.

Miller has felt the crunch personally, spokeswoman Vicki Fretwell said. He maintains his office in the State House, but some of his staff members are scattered in two other locations.

"People have been talking about this for 12 years," Fretwell said. "The James building is so crowded. Its handicapped access is not great. And the bathrooms? Let's just say the plumbing facilities leave something to be desired."

Miller has long been on a crusade to expand the Senate's facilities. "It's his baby," said Sen. Brian E. Frosh (D-Montgomery). "He's been pushing it for years. He's the prime mover."

Dave Humphrey, a spokesman for the Department of General Services, which is overseeing the project, said the annex will make the Senate more "orderly and predictable."

"Right now, there is so little room that people who are waiting to testify can't get access to the room. So they're pushed aside and have to wait outside. When their turn comes, the hearings have to stop while staff goes out into the halls to search for them," he said.

An old armory behind the James building was torn down in the spring to make way for the annex. There is now a large hole in the ground on the spot where a three-level underground garage with 140 highly desirable parking spaces for senators and staff is being built. The annex will be built above the garage. When completed, the Colonial revival-style building will be linked to the James building by a covered walkway and elevated skyway.

The new building will be completely wheelchair accessible and will have centrally located men's and women's restrooms on every floor. It will have two large multipurpose rooms with prep kitchens and theater seating for official functions, catered dinners and public meetings.

The interior decor has not yet been determined.

"Will it be a country club?" Humphrey said. "Far from it."

After the annex is completed in fall 2000, the Senate's nine top officers will move in. Then the James building is scheduled for renovation, Humphrey said.

"In the spring of 2001, the 38 senators will move into temporary quarters on the fourth floor of the annex while the James building is completely redone," Humphrey said. "All the office space will be reconfigured, the elevators repaired and asbestos yanked out."

Humphrey said the senators will be able to move back into the refurbished building in the late fall of 2002.

The upgrading of the Senate's facilities was never specifically approved by the General Assembly. Rather, the project was written into the state's capital budget last year. The contract was put out for bids in January. Five firms competed, and the bidding was won by the Coakley Williams construction firm of Gaithersburg.

CAPTION: A drawing shows plans for the Senate annex, right, and the James Senate Office Building, left.