DALLAS, FEB. 19 -- Rep. Jack Kemp (R-N.Y.) got a rare opportunity to take on Vice President Bush in a one-on-one debate tonight, but Bush grabbed the initiative to challenge sharply Kemp's commitment to arms reduction and deficit reduction.

In what initially seemed to have all the earmarks of a low-key confrontation, Kemp began to criticize Bush's unwillingness to support an antimissile system, when suddenly the debate took on a different character.

Just as Kemp was declaring, "I am a strong supporter of President Reagan," Bush interrupted to ask, "Then why don't you support the INF {Intermediate-Range Nuclear Forces} Treaty?"

Kemp countered by asking Bush whether he is confident the Soviets will keep their side of the bargain.

Bush replied: "I am confident that the INF treaty is in the national security interest. . . . I am not embarrassed to say I'd like a more peaceful world."

When Kemp attempted to argue that Bush made the mistake of placing a higher value on peace than freedom, Bush shot back: "I've been there. You don't know what it is like until you've seen your fellow man drop dead. I understand the perspective of someone who has fought for his country. . . . I understand what this country is really like, not some theory."

Kemp seemed caught off guard, unable to counter except to say, "We are a country that wants peace with democracy, not peace in our time."

The debate tonight was one of those rare moments in a presidential campaign when an underdog gets a clear shot at the front-runner, but the consensus here was that Kemp did not wound Bush, much less deliver a decisive blow. He was given the chance when both Sen. Robert J. Dole (R-Kan.) and former televison evangelist Pat Robertson refused to participate in the debate at Southern Methodist University, charging that the debate questions had been leaked in advance to Bush and that the event would turn out to be a "pep rally" for the vice president.

"I'm just not going to play," Robertson said. "It's going to be George Bush and his next vice president," he added, in a swipe at Kemp.

Dole denounced the event as a "George Bush pep rally," contending that Bush had gotten a disproportionate number of tickets. A Dole aide complained that Bush's wife, Barbara, had been given a front-row seat while Dole's wife, Elizabeth, had been assigned a fifth-row aisle spot.

"The only assumption that I can make is Dole has written Texas off," said an angered Burl Osborne, editor of The Dallas Morning News, which, along with The Texas Monthly, is sponsoring the event.

After the debate was over, Kemp sought to recoup at a news conference, charging that Bush's call for a four-year overall freeze in federal spending represents an accountant's "green-eyeshade mentality" that will "put the Republican Party a step backward, not a step forward." He accused Bush of attempting "to out 'Bob Dole' Bob Dole." Dole has called for an austerity program to restore balance to the nation's books.

The debate was designed to serve as the opening gun in the "Super Tuesday" battle, when 20 states, 14 of them in the South, will vote in what will amount to the largest primary to be held on a single day in the nation's history. More than half of the delegates required to win the GOP presidential nomination will be chosen March 8. Of all the states, Texas is the most imporant battleground, with 111 GOP delegates at stake.

Eddie Mahe Jr., a Republican consultant who is not affiliated with any of the presidential campaigns, said he thinks Dole decided not to participate because his temper had not cooled after losing New Hampshire to Bush. Polls had indicated that Dole briefly surged ahead in that contest, but when the ballots were counted on Tuesday, Dole had lost by 9 percentage points.

Before the debate, Kemp was delighted by the turn of events, declaring that it would take a "crowbar" to pry him from particating.

Some strategists in the Bush campaign attempted to press the vice president to back out, but there was too much pressure to keep his commitment to participate in his adopted home state, which he represented in Congress and where he maintains a voting residence by renting a hotel room.

Bush said he was confused by Dole's refusal, saying, "I honestly cannot interpret what it's about."