For the past 26 years, the black Democratic Ladies' Guild of Baltimore has remained loyal to the party, never endorsing a Republican candidate for governor of Maryland. In September's gubernatorial primary, it backed the Democratic winner, Harry R. Hughes.

But last weekend the 300-member group threw its general election support to the Republican nominee for governor, J. Glenn Beall Jr. The reason, plain and simple, was the presence of Dr. Aris T. Allen, the state's first black candidate for lieutenant governor, on Beall's ticket.

"This (ticket) tells our young people, if you get a good education and stay out of trouble, you can be governor of Maryland," explained Kitty Mueller, guild president. "This is integration at the highest magnitude. It doesn't have anything to do with the party."

Maryland's largest black population - which includes more than 750,000 people or almost a fifth of the state's total - has long been the safe preserve of Democrats. So safe that party strategists consider blacks the last loyal "bloc vote" in the state as other traditional Democratic voters, such as labor and Jews, show increasing independence at the polls.

Jimmy Carter owes his 1976 presidential election victory in Maryland at least in part by the black vote. While other longtime Democratic groups split their vote between Carter and then president Gerald Ford, blacks went overwhelmingly for the former Georgia governor - as high as 10 to 1 in many areas.

The black vote also is one of the most disciplined usually following the lead of Democratic officials and political bosses who control patronage and election day "walk-around" money. In the September primary, Acting Gov. Blair Lee III, who lost to Hughes, lined up support of almost every black political leader in the state and carried every black district by at least 2 to 1 over his nearest opponent. In Baltimore, where Lee handed black leaders more than $40,009 in "walk-around" money to pay election-day workers, the black districts were the only ones he won.

The voting characteristics of Maryland's black population are usually enough to discourage Republians, especially when faced with a Democratic candidate, like Hughes, who has a good civil rights record. Losing the black vote in places like Baltimre and Prince George's County often means losing the election in those large jurisdictions.

But Allen, the family doctor from Annapolis, far from being cowed by political tradition, expects to pull enough votes in the black precincts of Baltimore city Prince George's and Anne Arundel counties, and the Easters Shore to partially offset the commanding 3 to 1 advantage Democrats hold in voter registration statewide.

There is concern in the Beall camp that Allen's drawing power in black areas will be offset by a white back-lash in conservative pockets of the state. Beall, a more conservative politician than Hughes, is hoping to pick up support among blue-collar workers who traditionally vote Democratic.

In one incident that gave Beall advisers pause, a Harford County farmer who is a longtime Republican refused to allow Allen on his farm to pose for a campaign picture.

Allen is courting his fellow black Marylanders with a commutment never before seen in the black community, devoting a large share of his schedule to campaign in black welfare projects and shopping centers, speak to black businessmen and college students, and meet with black ministers and advertise in the local black media.

With less than two weeks left until the Nov. 7 election, there are signs the Republican strategy is paying off, especially in black Baltimore where Allen and Beall have concentrated their efforts. More than 40 per cent of the city's registered voters are black.

"Allen is catching on enough to get a split, predicted State Sen. Clarence M. Mitchell III, a black Democratic power. "We keep saying we want to get blacks in top state positions. You can't get much higher than the second position in the state.

"My people see this as an opportunity to make history."

In recent days the Republican ticket has been endorsed by the influential black Baptist Ministers Conference, whose members reach 100,000 church goers in Baltimore. Several prominent Demorcratic politcal leaders came to a Baltimore County fund-raiser for Beall last week. At least one important black Democratic organization is expected to support the Republican ticket, while some other Democrats have remained neutral so far.

Allen has not made the same in-roads in Prince George's County, where he has spent little time thus for campaigning among blacks, who make up nearly a third of the county's population. He expects to pick up support as he increases his apperances among the predominantly black population along District of Columbia line.

But Prince George's leaders say Allen will have trouble penetrating the solidly Democratic black areas where popular black politicians are actively supporting Hughes. "Aris is a helluva good man, but he's number two," said State Sen. Tommie Broadwater Jr., the county's preeminent black figure. "Beall never did a damn thing for blacks."

Maryland Republicans have not always had to work so hard for the black vote. Until the social programs of the New Deal brought them into the Democratic Party, blacks remained loyal to the party of Lincoln and emancipation.

In the first third of this century, white Democratic bosses despaired of winning the black vote. Their tactic on election day was to retain black lieutenants to pound up black voters, take them by boat to a picnic on an island off the Eastern Shore and stay there until the polls closed, according to an informal history of those times.

Beall and Allen are not the first GOP statewide candidates in recent years to court the black vote. Spiro T. Agnew carried black Baltimore by 22,000 votes when running for governor in 1966, giving him enough support to take the city from Democrat George P. Mahoney, who offended blacks with his stand against open housing.

What makes this election unique is that the Republicans seem to be picking up susbtantial ground even though Hughes is a liberal Democrat and Beall a conservative who as a U.S. Senator opposed school busing as a means of achieving racial integration.

Hughes has not pursued the black vote with the same enthusiasm as his opponents althoughs he has met with black political leaders campaigned in black areas and has promised to appoint blacks to high state posts, including at least one cabinet secretary.

But the Democratic nominee has not focused attention on black Maryland, according to campaign manager Michael Canning, because "We feel we'd be doing a disservice to single blacks out as speical group to be sought."