President Carter's attacks on Ronald Reagan as a racist warmonger, while helping bring back to the party fold some waverers in this blue-collar Democratic stronghold, have hardened anti-Carter sentiment among voters who backed him in 1976 and must be recaptured to carry Michigan and other pivotal states.

The president still falls short in blue-collar country. This was typified by a 30-year old auto worker who backed Carter four years ago but has been turned off by his slashing at Reagan. "Carter's trying to slam Reagan for only one reason," he told us. "He knows he is going to lose the presidency and he's panicking."

He was one of 63 registered voters whose homes we visited in several precincts in southern Macomb County, a lower-middle-income Detroit suburb filled with auto workers, many of them unemployed. Armed with a questionnaire prepared by Patrick Caddell's Cambridge Survey Research, we obtained these voter preferences (in votes, not percentages): Carter 29, Reagan 21, Anderson 5, undecided 5, won't vote 3.

That is a substantial decline from Reagan's dizzying heights last May when we interviewed in the same precincts. He then actually led Carter in this 3-to-1 Democratic area. But even Reagan's diminished strength in precincts that Carter carried by 62 percent while losing Michigan to Gerald Ford is bad news for the White House.

One-fifth of the 29 Carter voters and nearly two-thirds of the other 34 voters called the president's campaign "mean and negative." It is this reaction that prompted Carter's admission to ABC's Barbara Walters of "mistakes" in his anti-Reagan attacks even though "I don't think I'm mean, Barbara."

Our interviews confirmed White House concern over voter reaction to Carter's tactics. A 41-year-old insurance salesman told us: "Now that Carter's called Reagan a racist, I guess the next thing he'll do is go back to Reagan's Hollywood days and call him a red. Weren't they all commies out there in the '40s?"

Many pro-Carter voters, on the other hand, have been fortified by Carter's assaults on Reagan. "Reagan might end the recession real fast," said a 42-year-old housewife, "but we'd be in World War III quickly."

This suggests that Carter's strategy in painting Reagan as unsafe was good politics but was overplayed, alienating the pro-Reagan and undecided voters he needs. "I don't believe anything Carter says anymore," a 41-year-old mother of three told us.

This reaction spells special trouble for Carter with supporters of Rep. John Anderson. All but one of the five Anderson backers called Carter "mean and negative." These are voters the Carter camp desperately hopes will desert Anderson between now and Nov. 4 and come to the president. That prospect now seems lessened.

Despite Reagan's decline here from last May, these voters still give him a higher rating than Carter on "leadership," on "handling the economy" and, by almost 2 to 1, on giving the country "a strong defense."

Reagan's vulnerability on the war-and-peace issue shows up in answers to the question: "Which is better able to deal with the Russians?" When we asked that in May, Reagan edged Carter narrowly. Today, despite Carter's charge that Reagan wants to launch a "nuclear arms race" and has an itchy trigger-finger, Reagan is only slightly behind Carter: 25 of our voters with an opinion named Carter, 20 named Reagan as "better able" to handle the Russians.

Reagan actually has gained support for his demand that the United States spend more money on defense. While Anderson backers split down the middle, voters supporting Reagan favor increased defense spending by 8 to 1 and Carter backers by almost 5 to 1. Higher defense spending is a key Reagan campaign pledge, even though he has treated it gingerly in his campaign.

That conservative Republican Reagan continues strong in this Democratic auto worker heartland, depressed by the economy and anxious over the future of the country, is a portent for Nov. 4. If Reagan holds this support in hundreds of similar worker habitations across the country, he will win the election -- helped by the presidenths "meanness" backlash.