Jimmy Carter's role in the Panamanian election crisis has thrust him back onto the international stage eight years after leaving the presidency, and he says his relationship with President Bush is "infinitely better" than his relationship with President Reagan.

Carter, a frequent and harsh critic of Reagan after losing to him in the 1980 election, was asked by Bush to lead a team of international observers monitoring the national elections in Panama last week.Panama was one of the topics that most bitterly divided Carter and Reagan, so Carter's role as Bush's eyes and ears in the Central American nation vividly illustrates the change in his relationship from one administration to the next.

When he returned, he was quickly invited to meet with Bush, and he said in an interview Friday that Bush has been receptive to what he has to say.

"It's infinitely better," he said. "I had no relationship with President Reagan at all."

Carter's statements in Panama, in which he accused the government there of stealing the election, drew international attention.

Those who haven't followed Carter's activities may have thought he was re-emerging from a somnolent retirement. But in fact, the former president has been an active, if unofficial, player in world affairs since he left Washington in 1981.

Operating mainly out of the Carter Presidential Center in Atlanta, he has pursued favorite causes and offered the resources of his facility as an aid in mediating international disputes.

"I don't care for any official role," said Carter, speaking from his hometown of Plains, Ga. "I'm operating now in the same way that I've been for the last six or seven years. I think if I had an official role to play, it might hamper my freedom and limit greatly what influence or access I do have."

In the past few years, Carter has maintained an active schedule of speaking and traveling. In the past year alone, according to the Carter Center, he has been to Africa, Japan, Sweden, Norway, the Netherlands, Venezuela and Panama.

The Panamanian situation has special importance to Carter. In 1977, Carter signed an agreement with the late Gen. Omar Torrijos under which Panama is due to take control of the Panama Canal in 1999.

"Carter views the Panama Canal treaties as one of his most significant achievements, and all this represents some threat to his achievements," said Gary Fink, a history professor at Georgia State University.

Although some observers have questioned whether the United States should still honor the treaty with Noriega's abuses of power, Carter said in Panama last week that the United States would alienate the Panamanian people and "every other nation in this hemisphere" if it abrogated the pact.