Virtually every one of the ads for the reelection campaign of Michigan Gov. James J. Blanchard (D) has produced a complaint of negative campaigning or distortion from his Republican challenger, state Senate Majority Leader John Engler. Last week, Engler's camp caught a Democratic film crew using subterfuge to gather material for another ad, further fueling the controversy that has come to dominate Michigan media coverage of the race.

A film crew, saying it was working on a documentary for the Smithsonian Institution, showed up at the state capitol in Lansing and asked permission to film in the state Senate. Engler's office turned the crew over to the director of the Senate's restoration project, Jerry Lawler, who told the Detroit Free Press that he became suspicious when the crew focused mainly on Engler's desk.

The producer said she had no business card but gave her name as Kelly McMahon. A call to the Smithsonian adduced that it had no project on statehouse restorations and no employee named McMahon. But when Engler's people called the Washington office of Blanchard's media consultant, Robert Squier, they learned that McMahon is a television producer as well as Squier's daughter-in-law.

They quickly passed on their suspicions to Michigan reporters, and state Democratic Party spokesman Steve Gools acknowledged that the crew was on a campaign project. He apologized for its "overzealous behavior." Although Michigan news media identified McMahon as a Squier employee, she works for another Democratic consultant, Joseph Rothstein, who has a contract with the Michigan Democratic Party.

Rothstein told The Post: "I sent her out there to collect some footage inside and outside the capitol. When she was stopped from shooting inside the state Senate, she gave an erroneous story about what she was doing there. It was unfortunate . . . and we apologized."

Asked if the Engler camp was correct in surmising that the footage would be used to link him to the expense of the restoration, Rothstein said, "We don't have a plan to use that footage in a spot right now."