Senate Minority Leader Robert J. Dole (R-Kan.) routinely solicits and uses corporate jets to fly to events as he campaigns for the GOP presidential nomination, a lawful practice that critics say raises ethical questions and saves the Dole campaign many thousands of dollars.

Using an obscure provision in Federal Election Commission rules, Dole's campaign often pays the corporations that own the jets only the equivalent of first-class air fare for the Kansas Republican and any aides traveling with him. The corporation absorbs any additional cost of having operated the flight.

The arrangement provides a considerable convenience to the Dole, who can avoid the time involved in changing planes and in commercial airline delays and cancellations.

Some advocates of revising campaign-finance laws criticize the practice as a loophole that in effect permits contributions to candidates by corporations, which are barred from directly giving to campaigns.

Spokesmen for several other presidential campaigns said their candidates have not taken advantage of the provision.

The firms providing planes are involved in grain, oil, insurance and other industries that have issues of interest before the Senate, where Dole plays a crucial role as minority leader and a key member of the Finance and Agriculture committees.

"We have to try to keep the senator on the {Senate} floor as much as possible. And that's the reason we do it," said Scott Morgan, counsel for Dole's exploratory committee. He said that "trying to remain Republican leader in the Senate and trying to make a flight out of National and Dulles airports just wasn't working." He noted Dole is proud of his 94 percent voting-attendance record in the Senate.

So Dole's campaign staff now "calls around" to corporations with planes when scheduling campaign travel, Morgan said, rotating those used because "we don't want to make it look like one corporation is getting inside favor with the senator." A majority of Dole's campaign trips are now taken aboard corporate planes, he said.

According to FEC records, the corporations that have provided Dole with their planes for campaign trips since April include General Mills Inc., the cereal company; Coastal Corp., an energy firm; Browning-Ferris Industries Inc., a waste-management company; Warner Lambert Co., a pharmaceutical concern; ConAgra Inc., a grain company; as well as several insurance companies, including American Financial Corp., Metropolitan Life Insurance Co., Businessmen's Assurance Co. and Cigna Corp.

"When a congressman or senator asks for this kind of help, it gives us the opportunity to help them in a unique way," said Larry Alan, a spokesman for the U.S. Tobacco Co., which provided its luxurious Gulfstream III jet for Dole's trip to Iowa last weekend. "We've known Sen. Dole for many years and have admired his work." Dole has been an important ally for tobacco growers and cigarette manufacturers in supporting the tobacco-subsidy program and opposing higher taxes on tobacco products.

The 12-seat jet took Dole and three aides from Washington to Des Moines on Saturday, then ferried the candidate around the state for campaign appearances before returning here Sunday night.

The total cost to the campaign was $7,272. An official at Executive Air Fleet, a New Jersey-based charter company, calculated that chartering the plane for the trip would have cost $19,545, not including the flights within Iowa.

The FEC allows corporations and labor unions to provide planes and charge first-class fare if the travel is between cities that can be reached by commercial airlines. When traveling to cities without commercial service, the campaign must pay what regulations call "the usual charter rate."

Dole's prime rival for the Republican nomination, Vice President Bush, doesn't face the same problems in scheduling campaign travel. Bush routinely flies on Air Force Two for security reasons. Under FEC rules, his campaign is required to reimburse the government the equivalent of first-class fare for him and any campaign aides when he uses it to fly to campaign events.

Spokesmen for other presidential candidates said they are reluctant to take advantage of the FEC provision Dole uses because of what one called "the questions raised about whose jet it is and why it's provided."

Donald Foley, press secretary for Rep. Richard A. Gephardt (D-Mo.), said their campaign had "changed schedules, we've moved cities, we've cancelled events . . . to avoid putting ourselves in this situation and its questions." He said they have used corporate planes only as "the last of the last resorts." He said Gephardt most recently used a corporate plane, provided by Coastal Corp., in April when TWA cancelled a plane chartered to take him Waterloo, Iowa, for a major address.