There was a burst of publicity last October when E. Brooke Lee Jr. said he was exploring his chances of winning, as a Republican, Maryland's U.S. Senate seat now held by Charles McC. Mathias Jr., who is retiring after this year.

Lee was the first to toss his name, tentatively, into the ring. He became one of the first to pull it back out.

The 67-year-old Lee is a brother of the late former acting governor Blair Lee III. Their grandfather, the second Blair Lee, represented Maryland as a Democratic senator from 1913 to 1917, and their late father Col. E. Brooke Lee Sr. was Montgomery County's longtime Democratic boss.

Brooke Lee Jr. stepped into GOP ranks in 1982 to become a dark-horse candidate for mayor of the District of Columbia. He since has moved back to his ancestral Maryland where, in place of politics, he intends to help raise funds for the Bethesda-based National Foundation for Cancer Research.

For one thing, Lee told this column, he found that a race would cost $1 million or more of his own money without any solid prospect of winning. After the Fact

Some advertisers get more bang for the buck than they contracted for when they buy ad posters aboard Metro subway trains.

For example, subway car 1131, on the Orange Line, still displayed an interior poster last Saturday promoting Health Care Expo '85 at the Washington Convention Center -- which ended its seven-day run last Aug. 24.

But what the heck. Metro maps displayed at the McPherson Square station still list the 38A and 38B bus lines as running on 14th Street NW, which they haven't done for three years or more. Brinkleymanship

David Brinkley, cohost of a nostalgic party Sunday at the soon-to-close, family-owned Community Paint & Hardware store in Bethesda, was quoted in yesterday's Style section as saying:

"They (Community) are always here, unlike chain hardware stores, which have 18-year-olds in red blazers, who barely know what a hammer is and do not know what a screwdriver is."

Yesterday morning, Strosnider's Hardware, a couple of blocks away at Arlington Road and Bradley Boulevard (and described by my tipster as "at least the second-best hardware around"), posted this notice on its outdoor sign:

"Hey, David, we know the difference between a hammer and a screwdriver."

One clerk at Strosnider's, where the clerks do in fact wear red blazers, said the staff was a bit upset at Brinkley's comment.

"He shops in here, too," the clerk said.