Harry R. Hughes was making the rounds at a breakfast meeting of Montgomery County Democrats yesterday when he encountered the man who ran the county campaign of Theodore G. Venetoulis, one of the three men Hughes defeated to become the Democratic nominee for governor of Maryland.

"We've got hundreds of Venetoulis volunteers who are going to work for you," said Stan Gildenhorn, county Democratic chairman and Venteoulis supporter. And, he added, there are dozens of volunteers who worked for Acting Gov. Blair Lee III who will do the same.

Hughes smiled wryly, "Have you made any contact yet with my two volunteers in the primary?" he asked.

Hughes was only partly kidding. He shocked Maryland political oddsmakers two weeks ago when he easily won the Democratic primary with the thinnest volunteer organization in the four-way race.

His team was especially weak in Montgomery County where Lee and Venetoulis concentrated their efforts.

But the Monotgomery politicians and party workers who shunned his candidacy just a few weeks ago were outspoken Harry Hughes Democrats yesterday as they sipped coffee and munched breakfast rolls at Gene's on the Pike Tavern in Rockville.

"He's the only candidate nobody's mad at," explained State Sen. Victor L. Crawford. "If Veneoulis won it, the Lee people would have been mad. If Wally (Walter S. Orlinsky, the fourth candidate) won, everybody would have been mad. Harry Hughes was everybody's second choice."

The large breakfast gathering meant more than ironic satisfaction for Hughes. He ran a distant third in Montgomery County in the primary and needs the help of the county's normally fractions Democrats against Republican nominee J. Glenn Beall Jr. in the Nov. 7 general election.

Party Chairman Gildenhorn has promised that Montgomery County will run up the largest margin of victory for Hughes of any jurisdiction in Maryland. Venetoulis and Lee organizers already have assumed key roles in the Hughes campaign, he said, and several hundred volunteers once loyal to Hughes' rivals will make telephone calls and distribute literature for the Democratic nominee.

"Only Harry Hughes could have performed this miracel," said Gidenhorn. "He's Montgomery County's kind of candidate, thoughtful, intelligent, relaxed. The Kennedyesque type of candidate of the 1960s is not in vogue in the 1970s."

This was an apparent reference to Venetoulis, who styled himself after the Massachusetts political family.

Such gushing praise for Hughes may seem unusual coming from a man likd Gildenhorn who just a few weeks ago was a supersalesman for Venetoulis. But the party chairman typified the attitude of county Democrats who have recently achieved an unusual level of solidarity.

"They're all born-again Democrats," said Gene Diamond, owner of the Rockville eatery. "There's so much love here I'm going to turn this place into a health food restaurant."

Thomas Bratten, a member of Montgomery's Democratic Central Committee who backed Lee in the primary, promised Hughes his full support if the party standard bearer would return the assistance with a small favor.

It seems that Bratten so underestimated Hughes in the primary that he made a wager with a friend. "If Hughes wins. I told him, I'll kiss his tushy at Memorial Stadium at half time," Bratten recalled for the Democratic nominee.

"I'll do anything for you if you help me void that bet," he said in mock pleading tones.

"The way the Colts are playing," replied Hughes, "that may be the best play of the day."

Hughes, a native of Maryland's Eastern Shore who now lives in Baltimore remained characteristically reserved during the breakfast meeting, showing no special surprise at the warm welcome.

"I guess there's a difference between being the dark horse and the front-runner," he said.