WASHINGTON (AP) _ In a contentious, finger-pointing debate, Vice President Al Gore asserted Tuesday that Ross Perot will profit from defeat of the North American Free Trade Agreement. Perot dismissed the charge as ''propaganda'' to defend a deal that would punish American workers.

The prime-time showdown was combative from the outset, reflecting the high stakes in an extraordinary fight in which President Clinton is about 25 votes short and the pivotal House vote just a week away.

Hours before the debate, the White House got a much-needed boost - NAFTA endorsements from five House Democrats who had been undecided. A sixth, Rep. Jim Bacchus of Florida, announced his support just as the debate got under way.

Looking to win even more converts, Gore went after Perot and his anti-NAFTA arguments from the outset, surprising even NAFTA supporters who worried the vice president was too stolid to hold his own against the feisty Texan.

The debate on CNN's ''Larry King Live'' was but a minute old when Perot chafed that Gore was interrupting him. Tension crackled throughout the 90- minute program as the two traded a barrage of charges, some of them substantive, others more personal. The White House quickly claimed victory, citing Perot's silence when Gore demanded that he say how he would improve the trade deal.

Early on, Gore said Perot supported NAFTA in 1991 but flip-flopped as a presidential candidate last year ''to bring out the politics of fear.'' Later he upped the ante, saying a Perot family business in Texas stood to make huge gains as a trade center should NAFTA be defeated.

''If NAFTA is defeated, then this free-trade zone that he has is still in business,'' Gore said. ''If it's good enough for him, why isn't it good enough for the rest of the country.''

Perot was quick to fire back, denying his opposition to the agreement was motivated by any personal or family financial stake.

''I am putting my country's interests far ahead of my personal business,'' was Perot's retort. He said his gain would be ''something like a trickle of water.''

Perot accused the Clinton administration of putting up a smokescreen to hide what he said are the deal's many faults. ''The lowest and silliest trick,'' was his post-debate analysis of Gore's charges.

The debate was the climax of a frenzied day of NAFTA jockeying.

In a role reversal, Clinton served as warmup act for Gore, fiercely disputing arguments that dropping tariffs and other trade barriers with Mexico and Canada would send American manufacturing jobs rushing south to low-wage Mexico.

And, in a line Gore would echo hours later, Clinton said America would be stripped of its credibility in stalled trade talks with Europe and Japan should NAFTA be defeated.

''So the stakes here are very large, indeed,'' Clinton said.

Perot scoffed that such an argument was part of the administration's ''sky is falling routine.'' Every time Clinton falls behind, he claims ''the presidency is at stake,'' Perot said.

On that front, Perot got a boost from one of his odd allies in the anti- NAFTA coalition, House Majority Leader Richard Gephardt. ''We can do better,'' Gephardt said in urging Clinton to renegotiate the agreement.

Seated side-by-side, and often glaring at each other, Gore and Perot answered questions from King and from viewers in the United States and abroad, including one from Croatia.

The Gore salvos were part of a strategy that was evident from the outset - personalize the NAFTA fight in hopes of convincing wavering Democrats to choose their president over Perot.

But for all the theatrics, Gore and Perot broke no new substantive ground, trading familiar arguments over whether the trade deal with kill or create jobs and raise Mexico's labor and environmental standards.

Perot was first to use a prop - a photograph of slums in the shadow of a Mexican factory. The striking picture, he said, proved that low-wage Mexico was interested only in taking away American jobs, not in helping its people prosper.

''You will hear the giant sucking sound'' of jobs flooding to Mexico if the agreement becomes law, Perot said, repeating his trademark anti-NAFTA slogan.

He also said Mexicans were too poor to create the demand for U.S. products that Gore said would lead to more American jobs.

''People who don't make anything can't buy anything,'' Perot said.

In 1991, the average manufacturing wage was $15.45 per hour in the United States and $2.17 in Mexico, according to the U.S. statistics.

Gore had a chart - and photograph - of his own for his rebuttal.

The chart showed the United States has gone from a $5.7 billion trade deficit with Mexico in 1987 to a $5.2 billion surplus in 1992. ''They are buying a lot of products,'' Gore said.

The photo, which he presented to Perot, was of the authors of the Smoot- Hawley Act, a protectionist law that Gore said contributed to the Great Depression. Earlier in the day, Clinton framed defeating NAFTA as a similar retreat.

Gore accused Perot of repeatedly playing fast and loose with the facts, and in predicting previously that 40,000 Americans would die in the Persian Gulf war and that 100 banks would fail after Clinton took office. ''You were wrong,'' Gore said as he eyed Perot. ''The politics of negativism and fear only go so far.''

Getting personal, Gore said Perot's son supported the trade deal and that Perot himself did, too, ''until he started running for president and started to bring out the politics of fear.'' Perot endorsed NAFTA in a 1991 speech. He now says he changed his mind after learning the details.

Gore also said Perot would benefit financially regardless of the outcome of the NAFTA vote.

If it is defeated, Gore said, a Dallas-area Perot family business that has special trade status would be able to continue its tariff-free trade with Mexico. If the agreement is approved, he suggested that all business would benefit, including those owned by Perot.

''Would you even know the truth if you saw it?'' Perot retorted. ''I don't believe you would. You've been up here too long.''

Gore rebutted Perot's rebuttal, reading from a brochure of the Perot family business - one touting the Alliance Airport enterprise as an ''ideal distribution center for products coming out of Mexico.''

''He is in a position to benefit either way,'' Gore said.

''It's my son's business,'' Perot insisted.

As expected, Perot was feisty and ready with a barrage of catchy sound bites, at one point saying of Gore: ''He throws up gorilla dust. It makes no sense.'' For his part, Gore was sometimes studiously earnest but had a few zingers of his own.

''He started off as head of United We Stand,'' Gore said - invoking the name of Perot's political organization. ''I'm afraid he is going to end up as head of Divided We Fall.''