Those who have been expressing fear that the 1980 presidential race will be a gutter-level, mudslinging affair have new reason for concern.

On this coast, certain factions are attempting to plant the story among newspaper columnists about a purported homosexual affair involving a leading politico who has set his sights on the White House.

On the East Coast, active bidding is under way for publication rights to a Carter-administration expose being penned by Midge Costanza. Ms. Costanza, you remember, resigned as a presidential assistant last year and is now squarely in Ted Kennedy's corner.

And in Massachusetts, exteriors have just been completed for the $800,000 piece of cinema schlock to be called "Chappaquiddick," that will tell the story of you-know-what about You Know Whom.

Ms. Costanza insists the inside-theCarter-camp text she wants in release

Television

and radio

before the election "won't be vindictive. I will just tell the facts."

And actor Jack Knight, who's been signed to play Ted Kennedy in the film that will capitalize on the Chappaquiddick scandal, is trying to convince himself, and us, that the production won't influence votes or do anyone any harm. He's a staunch Kennedy supporter, he insists, and volunteers that he's actually going to try and contact Kennedy to get input for his portrayal, straight from the senator's mouth.

Bit actor-turned "Chappaquiddick" producer, Glenn Stensel, won't divulge who's putting up the money. He does cheerfully reveal he intends to have it in release by next summer when the presidential campaign will be in full swing, and he can expect, "It'll do big business."

Stensel is also more than happy to share some of the plans he's already plotting for "Chappaquiddick” publicity. Says he: "We might release some shots of the car going through the bridge or something."

Anyone for the Pepto Bismol?