Against the backdrop of next week's superpower summit, the Republican presidential contenders fought among themselves last night over the prospective treaty to eliminate mid-range missiles in Europe while the Democrats turned against each other over budget deficits and taxes.

In the first network television debate of the 1988 campaign, Vice President Bush was the only Republican who voiced unqualified support for the treaty President Reagan intends to sign next week with Soviet leader Mikhail Gorbachev, while most of his GOP rivals said the agreement would leave Europe's defenses weakened.

The six Democrats, who appeared on stage in alternating segments with the Republicans, found themselves in the ironic position of supporting Reagan on the treaty and blasting candidates of the president's party for their "appalling" failure to back him.

But the Democrats turned their fire on each other over how they would reduce the huge federal deficits of the Reagan years. Sen. Paul Simon (Ill.) was assailed for proposing an array of new government spending programs while also pledging to balance the budget. Former Arizona governor Bruce Babbitt accused his rivals of "flim-flam" on the budget and then dramatically rose from his seat and declared he was the only one willing to "stand up" and say he would raise taxes. And Sen. Albert Gore Jr. (D-Tenn.) zeroed in on Rep. Richard A. Gephardt (D-Mo.) for supporting one of the key planks of Reagan's economic program, his 1981 tax cut.

The two-hour NBC-sponsored debate, moderated by network anchor Tom Brokaw and held at the Kennedy Center, was the first in history in which the full field of candidates in both parties shared the same stage. While the format did not allow for face-to-face confrontations across party lines, the contenders went out of their way to aim barbs across those lines.

Among the more memorable moments of the evening: Former secretary of state Alexander M. Haig Jr., a Republican candidate, challenged Bush to say whether he was "in the cockpit or in an economy ride in the back of the plane" when Reagan approved trading arms for hostages with Iran. Haig's question played off the vice president's oft-stated claim that he participated in every major decision of the Reagan presidency as "copilot."

Without answering substantively on his role in the Iran-contra affair, Bush responded, "I think the Iran-contra report dealt with that." He went on to assail the bipartisan majority congressional report that had documented many of the abuses and deceptions of the scandal and to endorse instead the GOP minority report.

"You haven't answered my question," Haig insisted. "You are running for president and I think the American people want to know the position you took." Rep. Jack Kemp (R-N.Y.) said he would not hesitate to give presidential pardons to former national security adviser John M. Poindexter and fired National Security Council aide Oliver L. North for their roles in the Iran-contra affair. The other GOP contenders praised their patriotism, but withheld judgment on a pardon. Jesse L. Jackson drew laughter when he said "I've met more foreign leaders alive than anyone here." He deadpanned that the funeral-going vice president had the lead in seeing foreign leaders who were deceased. Bush later added his own touch of humor by observing that there had been so much hand-wringing among the Democrats that "I'm going to switch over and watch 'Jake and the Fat Man' on CBS."

The other candidates participating were Senate Minority Leader Robert J. Dole (R-Kan.), former television evangelist Marion G. (Pat) Robertson and former Delaware governor Pierre S. (Pete) du Pont IV. The Democrats were Simon, Jackson, Gore, Gephardt, Babbitt and Massachusetts Gov. Michael S. Dukakis.

The most sustained exchange on the Republican side came over an arms control treaty that Reagan has described as historic and a centerpiece of his presidency.

Bush noted that all the leaders of Western Europe had endorsed it and he described the INF pact as a "major breakthrough in verification."

Skepticism and opposition poured in from every other quarter of the stage. Haig said the treaty should be linked to a commitment from the Soviets to reduce their conventional arsenals, to stop engaging in regional conflicts and to halt human rights violations. He noted, in a reference to a Bush comment that most experts support the proposed treaty, that several, including former president Richard M. Nixon, former secretary of state Henry A. Kissinger, former national security adviser Brent Scowcroft and former U.N. ambassador Jeane J. Kirkpatrick all had reservations about it.

Kemp said "we should not rush into signing a treaty with the Soviet Union until we force them to comply with previous agreements" and said they had violated the SALT I and II strategic arms limitation accords, the Helsinki agreement and the 1972 Antiballistic Missile (ABM) Treaty.

Robertson said he "absolutely disapproved" of the INF treaty and predicted it would "effectively decouple U.S. power from NATO." He said that the United States and Europe would have to spend $50 billion to $100 billion to beef up conventional forces to compensate for the loss of the intermediate-range, nuclear-armed missiles, "and I don't think the political will exists" in the United States or Western Europe for such expenditures.

Du Pont drew a contrast between his opposition to the treaty and the unanimous support of it by the Democrats: "We defend freedom in this country; we don't just strive for peace."

Dole was the only Republican -- aside from Bush -- to leave enough wiggle room in his answer so that he might eventually vote for the treaty when it is put before the Senate for ratification. He is also the only GOP candidate for president who will have a vote.

"I am happy the president is signing it," Dole said, " . . . {but} we ought to be certain it can be verified." He said he wanted time to "read and study" the proposal, and suggested he would try to add provisions that would allow him to support it. "We can improve the treaty for the president," Dole said of the Senate ratification procedure.

In their foreign policy segment, the Democratic candidates repeatedly mocked Reagan's arms sales to Iran, sharply criticized his policies in Central America, questioned his policies in the Persian Gulf and assailed the "violations of law" by Reagan subordinates in the Iran-contra affair.

They also carefully skirted almost any serious disagreements among themselves. Instead they aimed their criticism at the Republican candidates and Reagan's record, prompting moderator Brokaw to quip that the Democats were a "pretty cozy little group."

But they went out of their way to point out that, unlike most of the Republican candidates on stage, they support the INF treaty.

Gore renewed his effort to stand out from the others by taking a harder line on defense and national security issues. He defended the U.S. involvement in reflagging Kuwaiti tankers in the Persian Gulf and at one point asked Jackson if he would now take the U.S. flags off the Kuwaiti tankers. Jackson said he would not, but that the United States needed to develop "multilateral patrols" in the gulf and called for efforts to win a cease-fire in the long Iran-Iraq war.

As they have in speeches on the campaign trail, the Democrats used the Iran-contra affair to poke fun at Reagan. "I brought {captured Navy flier Robert} Goodman back from Syria and didn't leave a cake and Bible with {Syrian President Hafez} Assad," said Jackson, referring to gifts brought to the Iranians by one of Reagan's former national security advisers. And Gephardt said Reagan had "put the Constitution through the shredder."

In their segment on domestic policy, the Democrats sparred vigorously over budget, taxes and the Reagan deficits. When Simon described himself as a "pay-as-you-go Democrat," Gephardt shot back, "You're a promise-as-you-go Democrat."

Gephardt, who has fallen behind Simon in recent Iowa polls, compared the plans of the Illinois senator to those of Reagan. "Simonomics is really Reaganomics with a bow tie," Gephardt said. Gephardt said Simon has supported spending programs that would give "free false teeth and free telephones for millions of people."

Simon was unapologetic. He said he would spend money now going for interest on the national debt for other purposes such as education and health care. He defended his plans for new jobs and education programs, vowing "we can do it" and adding, "I understand the figures."

Babbitt, who has called for a combination of tax increases and spending cuts to deal with the deficit, then fired back at the others. "I've just heard a lot of flim-flam," he said. He called for domestic spending cuts and a tax increases and accused the president, Congress and the other Democrats on the stage of refusing to "stand up" and tell Americans this. "And I'm going to stand up," he declared, rising and challenging the others to join him.

When they remained seated, Babbitt said, "There aren't a lot of profiles in courage here tonight."