ORLANDO, FLA., SEPT. 19 -- Vice President Bush, outlining the themes of his presidential campaign to a national convention of Republican women, today praised the nuclear arms accord that President Reagan and Soviet leader Mikhail Gorbachev are expected to approve.

But two conservative rivals for the GOP nomination said they fear that it could leave Western Europe exposed to Soviet aggression.

Bush told the National Federation of Republican Women that the proposed agreement to eliminate short- and medium-range missiles "for the first time in the nuclear age will reduce . . . the number of nuclear weapons and will verifiably ban an entire generation of these awesome weapons."

However, Rep. Jack Kemp (R-N.Y.) and former Delaware governor Pierre S. (Pete) du Pont IV complained that the proposed agreement would not reduce the Warsaw Pact's conventional-force advantage over the North Atlantic Treaty Organization (NATO).

"It separates Europe from the United States. And it does not speak to the conventional capability of the Soviet Union," Kemp said. "I object to the idea that you can just reduce one theater level of weapons without talking about the Warsaw Pact's preponderance of tanks and, of course, the first-strike capability that is still a threat to Europe."

Du Pont said that the proposed agreement "opens the 'window of gullibility' that Ronald Reagan closed seven years ago."

Like Kemp, he complained that "it appears to reduce nuclear arms in Europe without a corresponding reduction in tanks. They have twice as many of those, three times as much artillery and five times as many aircraft" as NATO forces.

He said Reagan should not sign the agreement without a protocol calling for some reduction in conventional arms and assurances that the nuclear arms reduction can be verified.

Kemp and du Pont did not voice these objections in their speeches to the convention, but made them afterward to reporters.

The other three Republican candidates, Senate Minority Leader Robert J. Dole (Kan.), television evangelist Marion G. (Pat) Robertson and former secretary of state Alexander M. Haig Jr., are scheduled to speak Sunday.

Bush told the 2,500 Republican women gathered here that "for the past seven years I've stood side by side with one of the greatest presidents this country has had -- and I'm proud of it. We've had triumphs and setbacks, but I'm not a guy to cut and run when the going gets tough."

But, "now it's time to define my own agenda, and I'm rarin' to go. Mark down Oct. 12. That's when I plan to announce I'm running for president," Bush said.

He listed five campaign priorities:

"Extending our progress on arms control."

Bringing economic progress to people and areas that have not yet enjoyed "the longest peacetime expansion in more than 100 years."

Achieving "a stronger sense of honor in public service."

Educating children for the 21st century and imparting values to them.

"Making protection of our environment . . . a Republican issue again as Teddy Roosevelt did way back at the turn of the century."