Worried that an anonymous political mailing by opponents of Baltimore County Executive Theodore Venetoulis is putting Maryland's gubernatorial campaign off to a bad start. Montgomery County Democrats have written each of the gubernatorial candidates and asked them to pledge to conduct a clean campaign.

The Maryland gubernatorial race is more than a year away. The primary will be held in September, 1978, and the election that November. However, several politicians including Venetoulis and acting Gov. Blair Lee III have indicated they plan to run.

ROy Dickinson, gubernatorial campaign liaison for the Montgomery County Democratic Central Committee, said the committee's letters to the candidates were prompted by two anonymous mailings critical of Venetoulis.

The first mailing, sent from Baltimore and received by all Democratic precinct workers in Montgomery County, contained copies of two articles from Baltimore newspappers that were critical of Venetoulis. A second mailing, with a Prince George's County postmark, contained two similar newspaper articles and was sent to the precinct workers and central committee members.

"It's not a good start," Dickinson said, "We're not happy about it. It's a way to start a war that really has no winners."

He said the Montgomery Democratic committee decided at a recent regular meeting to write the gubernatorial candidates about the mailings.

"We have no idea who else received them." Dickinson said. Lance Billingsly, chairman of the Prince George's Democratic Committee, said he knew of no such mailings being received in Prince George's County. But he speculated that Montgomery might be considered "more fertile ground" for the liberal Venetoulis, with Senate President Steny Hoyer running as a Prince George's favorite son.

Venetoulis's state political coordinator, Steven Gelobter, said he thinks the mailing "has not affected us adversely at all. The people in Montgomery County were just outraged and annoyed at these tactics being used against us one and a half years before the election."

Gelobter said he did not plan to file any official complaint or "make a big stink about it - however, the time may come when we will make a big stink about it." He added, "The (other) candidates tripped over themselves telling us that they didn't do it, and we don't have any idea who did it."

Dickinson said he wrote to "seven or eight" persons who have shown interest in the race.

In his letter to declared and potential gubernatorial candidates, Dickinson asked they pledge to conduct an open, clean primary campaign. He said he expects the candidates to respond favorably, though he said he realizes they cannot promise to control the actions of all of their supporters.

In other action, the Montgomery County Democrats recently adopted an affirmative action policy designed to increase the number of minorities in government and politics.

Committee chairperson James F. Doherty noted in the county Democrats' July newsletter, "Despite a black population of approximately 10 per cent, there is not one single black elected official in county government."

And he acknowledged that while the party organization has tried to recruit minority members as precinct workers, "our record leaves much to be desired." Among other things, the new affirmative action committee will encourage minority members to run for office and to take part in party affairs.