After months of public feuding, Maryland's leading Republicans tightened their ranks yesterday and unanimously endorsed Prince George's County Executive Lawrence J. Hogan Sr. in his bid to unseat incumbent Democratic Sen. Paul S. Sarbanes in the Nov. 2 election.

Although Hogan is virtually assured his party's nomination -- his chief Republican rivals withdrew from the race last month -- the display of unity was designed to discourage impressions that the state party is in disarray and that Hogan lacks support among party regulars. It was also aimed at attracting crucial financial support from the Baltimore business community, which has been reluctant to contribute to a Republican Senate campaign that until now appeared to have only lukewarm backing within the party.

This "marriage of convenience" between Maryland Republicans, as one party source labeled it, also reflects the national party's growing interest in the Hogan-Sarbanes race and the Republican view that Sarbanes is the most vulnerable incumbent in the Senate.

At yesterday's Capitol Hill press conference, state party leaders sought to shift the focus of the campaign from the party's infighting over Hogan to its chances to dislodge an incumbent Democrat this fall.

"We're here to make a point," said state party chairman Allan Levey, who had been less than enthusiastic about Hogan's candidacy in the past. "We stand 100 percent behind Larry Hogan. If there is anyone in Maryland who can beat Paul Sarbanes, it's Larry Hogan."

Echoing Levey were Maryland's top Republican leaders: Sen. Charles McC. Mathias and Rep. Marjorie S. Holt; former U.S. Senator J. Glenn Beall, whom party regulars had courted as an alternative to Hogan; V. Dallas Merrell, a Silver Spring businessman who jumped in and out of the primary race several times before finally withdrawing last month; former professional football player J. Michael Curtis, who also withdrew last month; and Louise Gore, a well-known Republican from Montgomery County who defeated Hogan in the gubernatorial primary in 1974, his only other bid for state-wide office.

Hogan's problems with party leaders stem from his efforts in 1980 to become the Maryland GOP's delegation chairman to the national convention, which party regulars (including Holt and Mathias) viewed as opportunistic and heavy-handed. Some Republicans also criticized Hogan last year for "pushing" his son, Lawrence J. Hogan Jr., to run for the 5th District congressional seat vacated by the ailing Gladys Spellman when other viable and better-known Republicans were in the race. Hogan maintains that he tried to discourage his son from running.

Unlike Maryland's GOP gubernatorial candidate, Robert A. Pascal, Hogan has relied on and taken advantage of national party resources and advice and will receive a campaign contribution of $230,000 in September. According to some party sources, he needed to solidify his Republican base in Maryland to continue to receive help from the national party. He accomplished that with the press conference yesterday, the sources said.

"The campaign is back on track," said one leading Republican who asked not to be named. "People put down the muskets long enough to realize that it's easier to be friends. It's a shaky truce to start with, but it has great potential."

Despite the public enthusiasm that Republicans now voice for Hogan, his campaign faces several serious obstacles. According to the most recent Republican party polls last February, Hogan is not well-known outside the Washington area. Although his campaign officials are heartened by a recent surge of campaign contributions, he has raised only $267,000 to date, one-third the amount Sarbanes has raised. Hogan says he will need an additional $900,000 to run a competitive race.