Beginning Monday, when a banner calling him an assassin was hung outside the Rayburn House Office Building, it has not been the smoothest of weeks for Rep. John D. Dingell (D-Mich.).

The Detroit congressman's critics lobbed another salvo at him yesterday, this one in the form of a Ralph Nader "white paper" calling Dingell Consumer Enemy No. 1 in Congress.

Nader's Congress Probe research organization released a 25-page study of Dingell's recent legislative actions, describing him as a one-time consumer-environment ally who had gone bad.

"Given his position, his power, his drive, his corporate allies and his Machiavellian skills, Dingell can now be considered the number one enemy of consumers on Capitol Hill," Nader wrote in a foreword to the study.

Consumerist Nader said he regards the report as "a battle cry for the consumer movement," which he hopes will deter the House from picking Dingell to head the Commerce Committee.

Dingell and Nadar have tangled before, largely over sensitive auto safety and energy issues, but the congressman and his staff were not taking the bait yesterday.

Dingell's office said there would be no comment on the Congress Probe study until the congressman has had a chance to review it.

The impetus for this week's blasts at Dingell is the furious debate over air bags in new automobiles. Dingell has riled safety advocates with his opposition to air bags.

Air bag supporters argue that by opposing the devices, Dingell and his congressional allies are contributing to unnecessary highway deaths. Dingell has contended that the bags are an expensive impediment to safety.

The issue soon will reach the House floor again, when a House-Senate conference report is debated. The report -- contrary to Dingell's position -- will require some safety air bags in new cars beginning in 1983.

Anticipating an all-out push by Dingell to scuttle the confernce report, his foes began filtering out of the woodwork this week.

Early Monday, the Rayburn building was festooned with a huge banner that read, 'WANTED: John Dingell, Airbag Assassin." Leaflets in the same vein was distributed by protesters, with whom Nader yesterday claimed no affiliation.

Air bag proponent Rep. James H. Scheuer (D-N.Y.) said that upon seeing the leaflets, he promptly called Dingell to disassociate himself from the protest, which he called "poisonour and cowardly."

Scheuer, chairman of the consumer subcommittee, has differed bitterly with Dingell on consumer issues in recent months, a dispute that is treated in the Congress Probe study.

Nader alleged in his foreward that Scheuer had been warned, through Rep. James Broyhill (R-N.C.) that his subcommittee chairmanship might be in jeopardy if Dingell, as is expected, becomes full committee chairman next year.

Scheuer confirmed that he and Broyhill had talked but said that Broyhill's remarks were "tongue in cheek, in no sense worthy of outrage."

Nader said that Congress Probe will attempt to publicize Dingell's record in his metropolitan Detroit district this fall and, if he is reelected, will work to prevent his succession to the Commerce Committee chairmanship.

The study outlined a series of issues on which Dingell had moved during the last decade from "a liberal to . . . a corporate-interest pleader" who brandishes his personal power over House colleagues to get his way.

The study concentrated on Dingell's activity on environmental, safety, energy and political reform subjects tracing position changes that Congress Probe called anticonsumer.

"With John Dingell," Nader said, "there is no time to temporize further.It is a time to stand up in the halls of Congress to him and the reckless intersts which nourish and feed off his power."