Republican George Bush vowed Friday to "never, ever under any circumstances" pay reparations to the Iranian government for the downing of a civilian airliner, though he said payments to victims' families are being considered. Democrat Michael Dukakis said he favored "humanitarian assistance" in the case.

Under the torrid summer sun, it was a day for each of the nominees-to-be to campaign hard on the other's turf.In Atlanta, where the Democrats gather in 10 days for their national convention, the vice president tried to shrug off Democratic charges that his cash-starved campaign was illegally using tax dollars to keep going.

In Texas, where Bush votes, Dukakis campaigned with a potential running mate, home-state Sen. Lloyd Bentsen, amid indications that the Massachusetts governor's search for a vice presidential choice may be entering its final days.

"I'm pondering," Dukakis said of the Senate Finance Committee chairman at a rally in Texarkana, Texas. "He could make a great contribution in this country in many, many ways. He already has."

Bentsen seemed to minimize his chances of being the choice, saying when asked if he wanted the job, "I don't think we have to worry about that."

Dukakis also campaigned in Phoenix, accompanied by former Arizona Gov. Bruce Babbitt, a former nomination rival, and Gov. Rose Mofford. He then left for Los Angeles.

With new pressure on the Democratic nominee-to-be from Jesse Jackson's camp, Dukakis campaign chairman Paul Brountas and Jackson put off a meeting to discuss the vice presidential situation.

Jackson campaign manager Gerald Austin said Dukakis should not pick presidential also-ran Albert Gore Jr. of Tennessee, one of the men under consideration. But Jackson himself said in Dallas that Austin was speaking for himself and that he, Jackson, had "not made any negative statements, either privately or publicly" on other vice presidential prospects. "It would be unethical to do so," he said.

He said his campaign has no veto over Dukakis' choice and does not "choose to exercise the appearance as though we have a veto over anyone in the process."