DES MOINES, Iowa-Vice President George Bush backed off yesterday from charges his campaign has been leveling at chief GOP presidential rival Kansas Sen. Robert Dole as candidates of both parties began cooling their rhetoric on the eve of Iowa's crucial precinct caucuses.

The Democrats, with a tightly bunched group of frontrunners, focused on attacking U.S. policy in Central America, with Massachusetts Gov. Michael S. Dukakis suggesting he would be willing to tolerate a Soviet client state in the region as long as it was not "a platform for offensive military operations or the subversion of neighboring governments."

Bush, appearing on ABC's "This Week with David Brinkley," offered to "totally apologize" to Dole's wife, Elizabeth, if a Bush campaign statement offended her, but declined to extend an apology to Dole.

"I don't think he's mean-spirited," Bush said. "But I don't think the charges that that campaign has leveled against me over and over are true at all."

Bush was questioned about a statement issued by his Iowa campaign manager, George Wittgraf, which attacked Dole for "mean spiritedness" and raised questions about the management of his wife's finances.

"I looked at that and saw nothing that I felt was a criticism of Elizabeth, but if so, I would totally apologize to her," Bush said. "She's a friend."

Dole, interviewed on NBC's "Meet the Press," said of the feud with Bush "as far as I'm concerned it's over."

But Dole could not resist a shot at Bush on the Iran-Contra arms deal.

"I do think there's a feeling out there that somehow, obviously, Bush is more closely tied to that than any of the rest of us," Dole said.

Absent Gore

The campaign flurry came as 11 of the 13 Republican and Democratic presidential candidates stumped across snowy Iowa, with only Sen. Albert Gore Jr. (D.-Tenn) and former Secretary of State Alexander Haig staying away.

It comes on the heels of a survey showing Dole with a double-digit lead over Bush in a poll published by the Des Moines Register, while indicating Missouri Rep. Richard Gephardt led Illinois Sen. Paul Simon and Dukakis among the Democrats.

The candidates planned an exhaustive series of speeches as they urged supporters to turn out in each of Iowa's 2487 precincts today. It is the first test for Democrats, and an important early battle for the GOP.

Appearing at a Cedar Rapids, Iowa, breakfast, Gephardt bragged about last Wednesday's House vote rejecting aid to the Nicaraguan Contra rebels.

"For six long years, we've had this senseless policy of sending our tax dollars to soldiers in Nicaragua," Gephardt said. "Last Wednesday night we decided in the House of Representatives that we couldn't wait untilNovember to change America."