John B. Anderson, the Republican evangelist of "new politics," is in danger of becoming last month's hero in next month's Wisconsin primary.

Two weeks ago, the snowy-haired Illinois congressman was the hottest political property in this state. He had become the darling of the campuses, the favorite of a new generation of students who have played crucial roles in past presidential campaigns here. Independents and liberal Democrats were flocking to his campaign.

"If our primary would have been held the same day as the Illinois primary [March 18], there's no question in my mind that we would have won," says Ann Peckham, Anderson's state chairman.

But time and the primary system appear to have conspired against Anderson. In just two weeks, his image has been tarnished by primary losses in his home state of Illinois and in Connecticut. As Wisconsin's April 1 primary approaches, he is attacked from all sides.

On the right, supporters of Ronald Reagan are saying he is too liberal. On the left, California Gov. Edmund G. Brown Jr. is accusing him of being anti-labor, pro-Vietnam war and pro-nuclear power. And in the middle, George Bush is saying Anderson isn't Republican enough.

Sen. Edward Kennedy's upset victory in the New York Democratic primary yesterday raised new interest in the all-but-dead Kennedy campaign here, siphoning potential liberal votes away from Anderson. Bush's win in Connecticut may have revived his stock among Republican moderates. And some Anderson strategists fear the crossover Democratic vote once expected to help their candidate may actually benefit Reagan, who has so much blue-collar, conservative Democrat support.

In short, next Tuesday's Wisconsin Gop primary has suddenly become a new ballgame. "It's as much as tossup as anything I've ever seen," says Ody Fish, a veteran of two decades of GOP wars.

Anderson advisers have long deemed Wisconsin's large student population and history of progressive politics ideal for their candidate, and he has spend an average of four days a month in the state since last August.

Wisconsin has the most open primary system in the country.Regardless of previous party affiliation, voters are allowed to participate in either the Democratic or Republican primary, and they can even wait until Election Day to register.

Anderson's stock in the state skyrocketed after his surprise second-place finishes in the Vermont and Massachusetts primaries. The same campuses that spawned the anti-war protestors who gave Eugene McCarthy and George McGovern Wisconsin primary victories sprang alive for the first time in yerrs, reaching out to the lonely longshot candidate battling all the odds.

After the Illinois primary, according to the state campaign chairman Peckham, "The pace just slowed. We didn't have as many calls. We didn't have quite the number of volunteers. And we noticed a little lacklusterness among the people coming into the office."

The poll published in Sunday's Milwaukee Journal showed Reagan supported by 24 percent of the people likely to vote next Tuesday, compared to 19 percent each for Anderson and Bush, who is said to have the best organization in the state.

Anderson, meanwhile, has begun to sound more like a crusader for his brand of "new politics" than a potential GOP nominee. "He almost sounds like an evangelist with a new cause," says Fish. "It seems to me he's getting carried away with his audiences."

Anderson has also begun to talk more and more about the possibility of an independent third-party candidacy -- somthing he repeatedly rejected in Illinois just two weeks ago.

"This is a matter that is being increasingly urged on me, and there are people who are talking more and more about the possibility," the 20-year House member said yesterday. "And I have learned over my years in politics to at least give people a respectful audience and listen to what they have to say.

"I've not totally disregarded that option," he added, while saying he still hopes to become the Republican presidential nominee.

For now, Anderson is as committed as ever to getting the Republican nomination, his campaign manager, Michael MacLeod, said today in Washington. After next Tuesday's primaries, Anderson intends to try to win delegates in Pennsylvania, where he is not on the ballot, and then shoot for a victory in Indiana's May 6 primary.

MacLeod met with Anderson Tuesday in Wisconsin, and in the course of that strategy session they touched on the issue of an independent candidacy. "Calling it a serious discussion would be exaggerating it," he said. "When you get down to discussing strategy it's an option, and it was discussed. But Anderson persits in the belief that the Republican nomination isn't sewed up."

His advisers are divided, with some believing he should declare an independent candidacy as soon as possible, others believing he should at least try first to win the nomination, and still others who oppose it altogether.

Still, such talk is smart politics in an independent-minded state like Wisconsin, according to Anderson pollster Richard Bennett. "In Illinois, we blew it. We got into a fight over who was a better Republican. That wasn't what independents wanted to hear."

"He has to concentrate on getting independents and Democrats to vote for him," adds Bennett.

If a rally on the outskirts of Milwaukee last night is any indication, Anderson is succeeding. It was hard to find a Republican in the crowd of more than 350. Most present were young liberals. Many had supported Rep. Morris Udall (D-Ariz.) four years ago.

"I've never voted Republican in my life," said Don Lipke. "But I might this time. I don't think we have a good choice on the Democratic side. Anderson may be the [WORD ILLEGIBLE] in the [WORDS ILLEGIBLE] he appears to be the most honest.