The prospect of a two-man debate between President Carter and Ronald Reagan was revived yesterday, as strategics for the Republican nominee said Reagan will consider such a debate if the League of Women Voters decides that independent John B. Anderson is no longer a viable candidate.

President Carter's campaign chairman, Robert S. Strauss, predicted yesterday that the league will decide just that. And, stepping up the pressure on the former California governor, Strauss sent Reagan a telegram stating that both Carter and Reagan "owe the voters an opportunity to compare your positions in a public debate" and asking Reagan for an "immediate favorable response."

The renewed discussion for a face-to-face debate between the two major party presidential nominees was a result of a statement by the League of Women Voters that it was reassessing its position on whether Anderson remains a viable candidate worthy of inclusion in a debate among presidential candidates.

Reagan's advisers had decided several weeks ago, on the basis of internal polls, that the former California governor had a solid lead over Carter and ought not to risk it in a debate. Last week, however, those polls showed a small dip in several key states. Campaign aides said yesterday the decline had since been reversed, but a number of Reagan's advisers fear that if the league declares Anderson ineligible for future debates, Reagan could be hurt by refusing to appear with Carter.

Reagan's advisers believe their candidate still leads Carter, but chief of staff Edwin Meese said yesterday that Carter had scored points on Reagan with the "war and peace" issue.

Carter, campaigning in Lyndhurst, N.J., said he was prepared to participate in the debate.

The prospects of a debate involving the major party nominees had been at an impasse. Carter refused to participate in a Sept. 21 debate that included Anderson, and Reagan has consistently refused to meet Carter in a debate that excluded the independent candidate. But this week the Gallup poll published a survey showing that Anderson had plunged from 15 percent to 8 percent among likely voters. The poll showed Reagan at 45 percent and Carter at 42 percent.

James A. Baker III, Reagan's c hief negotiator on the debate issue, emphasized that Reagan still believes Anderson should be included in any presidential debate.

"The only thing that could change anything is if the league no longer found Anderson a visable candidate," Baker said. "If that should happen then we will take a look at the one-on-one debate proposal. But we're not going to abandon principle, and we would hope that the league wouldn't shave principle either."

There has always been a division of opinion within the Reagan camp on whether Reagan should debate Carter. One group of advisers believed it would be unwise for Reagan to risk the lead they felt Reagan had. But others in the campaign argued that Reagan would do so well in a confrontation with Carter that it would solidify a Reagan victory -- just as Reagan wrapped up his New Hampshire primary victory in his debate with George Bush.

But there is another lesson from the past winter's campaign that could tilt Reagan toward deciding to enter into a debate with Carter. It is Reagan's realization that it proved costly -- and almost politically fatal -- for him to have ducked that January multicandidate forum with other Republican presidential hopefuls before the Iowa caucuses.

At the Carter headquarters, even as he was applying renewed pressure to force Reagan into a debate, Strauss was saying that the latest data from Carter's pollster, Patrick Caddell, show the president pulling ahead, or at least even, in all of the key industrial states.

These states will be decisive in the election, Strauss said, and Reagan had been ahead in all of them. ". . . Carter does not need the debate. Reagan needs the debate," he said.

Meanwhile, on the Reagan campaign plane, Reagan political strategist Stuart Spencer was saying, "We don't need a debate. We're not behind. We haven't seen one national poll that gives us cause for worry."