With his presidential campaign heavily in debt and losing support from the "New Right," Rep. Philip M. Crane (R-Ill.) yesterday fired his campaign manager.

In a statement, Crane said Rich Williamson, a young Washington attorney, had been replaced by a longtime friend, Jerry Harkins, a Donaldson, Iowa, banker who worked in Sen. Barry Goldwater's 1964 GOP presidential campaign and Ronald Reagan's 1963 effort. Williamson was formerly Crane's administrative assistant.

The move, expected to lead to a wholesale realignment of Crane's campaign staff, comes at a time when some "New Right" groups supporting Crane are backing off because they believe he is diluting his positions on conservative social issues.

So far, the immediate beneficiary of the disenchantment appears to John B. Connally. Sources said Connally's staff is contacting some of the disaffected New Right leaders.

Crane vigorously denies he is changing his position on New Right issues such as abortion, neighborhood schools, gun control and the Panama Canal treaties, but he admits he has been stressing economic issues and national security policy more.

He also admits he "had a disagreement" with conservative direct-mail fund-raiser Richard Viguerie over how much money to put into direct mail. Crane said he would cut down on what his campaign would spend on direct-mail "prospecting" - looking for new supporters - because if he accepts federal matching funds for his campaign it would cut down on what he could spend on other campaign items.

Crane said he would not cancel his contract with Viguerie but would cut down on the amount of money involved.

Through Viguerie's direct-mail operation, Crane has spent $2 million to raise $1.7 million from more than 70,000 contributors. As of March 31, Crane's campaign was $888,000 in debt, $461,000 owed to Viguerie's operation.

It is not clear whether Viguerie might take on another presidential candidate as a client while having a contract with Crane. Viguerie could not be reached for comment.

Paul Weyrich, director of the Committee for the Survival of Free Congress and one of the most influential New Right leaders, according to Human Events magazine, had been scheduled to take over Crane's campaign field division.

But he says Crane is "no longer comfortable" talking about abortion, gun control, neighborhood schools or the Panama Canal, and accuses him of "being off on an image-type operation" and becoming "just another smiling, friendly face we can elect."

Weyrich said the early campaign strategy had been based on a coalition theory - that Crane would structure his campaign to be attractive to conservative Republicans and to try to pick up support among more conservative ethnic urban Democrats disaffect with their party.

"He has completely backed off on this. George Bush has become a harder-line candidate in this area than he has," Weyrich said.

Weyrich said he is uncertain about whether he will switch to another candidate, but sources said he has been talking to the Connally camp.

Peter Gemma, coordinator of the National Pro-Life Political Action Committee, met last month with Crane aides to discuss Crane's position on abortion. Gemma later told Human Events that he was still a Crane supporter, "but to say I've become disillusioned is a great understatement."

Crane vigorously denied he has changed his positions. He said he still supports a constitutional amendment to ban abortions, and continues to oppose the Panama Canal treaties.

"I am focusing on economic questions that are bothering so many people," Crane said. "But I challenge them to demonstrate just where I've revised my stance or backed off. Where is the evidence? You can't find it."

Asked whether the loss of support from New Right leaders would hurt his campaign, Crane said, "I don't think I'll lose them. I certainly won't lose those who share a common philosophy of freedom with me. I don't want to seem immodest, but I'm the only candidate they've got."