Steny H. Hoyer was being as unobtrusive as possible, standing out of camera range while his new political bridegroom, Acting Gov. Blair Lee III, chatted with reporters about his choice for lieutenant governer.

Suddenly, the press conference turned to Hoyer, the 38-year-old Prince Georgian who gave up his own gubernatorial candidacy as well as the presidency of the Maryland Senate to take the second spot on Lee's ticket.

Hoyer was asked whether he had apprised his friend, Baltimore Mayor William Donald Schaefer, of his decision to join the Lee ticket, and, if so, whether the popular mayor had indicated any plans of his own for the gubernatorial race.

"I did speak to the mayor yesterday morning (last Wednesday)," Hoyer replied, "and did tell him about my intentions . . . It was my belief that he is not running. That was not specifically stated in the conversation."

"What makes you believe that?" came the next question from the press corps.

"What makes me believe it?" a smiling Hoyer retorted, as if playing off a straight man in a comedy act. "Because he didn't ask me to run for lieutenant governor with him. Believe me, he's the only one (who didn't)."

Hoyer's quick wit was well appreciated by Annapolis reporters, who chuckled heartily. But his decision to run with Lee came as no laughing matter to the other four Democratic candidates in this fall's gubernatorial race.

Like spurned lovers, they struck back at Hoyer, accusing him of cynically cutting a deal with old-line political and monied interests.

Lee also received some rough handling. As a Montgomery County resident, his opponents charged, he skewed his ticket in favor of the Washington suburbs by selecting Prince George's Hoyer. "Caveat Baltimore," came the warning.

By the end of last week, heavy blows had been landed by three of Lee's rivals - state Attorney General Francis (Bill) Burch, Baltimore County Executive Theodore G. Venetoulis and former state Transportation Secretary Harry R. Hughes.

Only Baltimore City Council President Walter S. Orlinsky remained above the fray. True to his flair for the unconventional, he praised Hoyer and congratulated Lee for his good fortune in landing him.

More than any other single event in the developing gubernatorial sweepstakes, the merger of Lee and Hoyer gave definition to the wide-open contest, forcing other candidates to reexamine their own standings and strategies.

Hoyer was the most attractive candidate in Maryland for the second spot on a gubernatorial ticket. In addition to his yen for campaigning and his experience, he brings Lee a strong political base in Prince George's and a following in the General Assembly.

The political marriage came at the worst possible time for Lee's opponents. It strengthened the acting governor a few days after a Baltimore newspaper poll showed him way out in front in his drive for the Democratic nomination.

It also created an atmosphere of desperation for Lee's rivals. Each responded resourcefully, neatly fitting Hoyer's decision into his own campaign theme and hoping to capitalize on a move each must have dreaded a few days earlier.

For Venetoulis and Hughes, who both sell themselves as reform candidates, the alliance confirmed the suspicion that Lee and Hoyer were no better than their political forebears in Maryland, all backroom politicians in a corrupt state.

"This was a clear drawing of the lines," said Jackie Smelkinson, who runs Venetoulis' campaign. "It makes it clear that the voters can decide whether they want the old political deals or something entirely different."

For Burch, the merger smacked of political regionalism. Barging into the Hoyer press conference where the new ticket was unveiled, he said the election was now between the "varied interests" in the Washington area and "the Baltimores."

The themes of "regionalism" and "backroom deals" will be sounded often throughout the campaign, even though they have a ring of exaggeration when held up against the records of the two targets, Lee and Hoyer.

Lee is a practical politician who knows the game of power politics as well as anyone. But he brings an openness to state government that maddens his political advisers.

What other politician in Maryland would grant interviews to reporters in which he laid out the fine details of his marriage vows to Hoyer, including a promise that his lieutenant governor would have the right to dispense patronage to Prince George's?

The "regionalism" charge is equally stretched. Despite a couple of off-hand remarks about Baltimore's appetite for the state budget, Lee has always had a sympathetic ear for the city's problems, as any city legislator would attest.

What's more, Hoyer is held in the highest esteem by the city's strongest lobbyist, Mayor Schaefer, who now says he feels more comfortable with Lee's candidacy because of the Senate president's long appreciation of Baltimore's interests.

When the election really gets down to business, the voters will have a wide selection of candidates who vary more in style than substance. The electorate in Maryland votes for personality, not ideology, if history is any guide.

The Burch campaign style has emerged forcefully in past days. A millionaire businessman, he casts himself as a modern-day populist with a conservative strain who will not abide by tradition when it comes to speaking up for "the little man."

Last weekend, he jettisoned any chance of getting the support of Maryland's powerful teachers union by telling the group at its annual convention that teachers are overpaid and have failed in their job of educating children in the state.

Venetoulis, a 44-year-old Baltimore Countian with boundless energy and a contagious, youthful campaign style, hopes to offer a stark contrast to the 62-year-old Lee, who admits he is not comfortable in the role of a back-slapping politician.

But Venetoulis, whose eagerness for publicity has earned him the sobriquet "TV Teddy," risks coming across too glib in his "boy next door" approach to the voters The boy next door image is not always considered "gubernatorial."