After months of distant shadowboxing, Vice President Bush and Senate Minority Leader Robert J. Dole (R-Kan.) have started slugging it out in the fight for the Republican presidential nomination.

Until last Monday, Dole had been taunting Bush for weeks with stinging gibes that got no response. When the new year opened, Bush stopped ignoring them and started to fight back. With the Iowa caucuses only a month away, the two leading contenders for the GOP nomination have spent the last seven days in virtual hand-to-hand combat.

It has become an intensely personal rivalry -- the kind that is supposedly prohibited by the party's 11th commandment: "Thou shalt not speak ill of another Republican."

Bush campaign lieutenants are trying to take the lustre off Dole's proffered image to Iowa voters as "one of us" by calling attention to the personal wealth of the senator and his wife, former transportation secretary Elizabeth Hanford Dole. Bush called for the release of 10 years of tax returns and his aides circulated over the weekend an article in a Kansas newspaper raising questions about a financial transaction involving Elizabeth Dole's blind trust and a former aide whom the senator helped with a government contract.

Dole accused the Bush campaign yesterday of distributing derogatory information about his wife and compared it to the damaging videotape about Sen. Joseph R. Biden Jr. (D-Del) that was distributed by aides of one of his rivals, Massachusetts Gov. Michael S. Dukakis, which helped to force Biden out of the race.

"I think what's he trying to do is shift the focus from credibility on the Iran-contra thing to something else," Dole said in an interview on the ABC News program "This Week With David Brinkley."

The thrust of Dole's offensive has been to pressure Bush for more information about his role in the Iran-contra affair. Dole said yesterday that Bush should reveal what he told President Reagan about the Iran arms deals, which Bush has refused to do.

"After all, confidentiality is to protect the president, not the vice president," Dole said.

Dole added that if Secretary of State George P. Shultz and former Secretary of Defense Caspar W. Weinberger could say what they told the president, "I'd bet if George Bush asked Ronald Reagan, 'Is it all right for me to tell what we talked about in that meeting?,' knowing President Reagan, I think he would say, 'Go ahead, George, tell the American people what you said, and what reservations you had.' "

"I would have flatly opposed it, arms for hostages, or arms for Iran, in any event," Dole said.

Before last week, Bush had given only partial accounts of his role, refused to say what he told Reagan and chafed at questions about the scandal. But with renewed focus on the question, Bush decided he had to mount a new and more aggressive political defense, aides said.

In doing so, Bush did not reveal any new information about his role or his private advice to Reagan, and he stuck by his assertion that he did not hear the objections of Shultz and Weinberger to the arms sales. But the vice president adopted a more open and combative approach, insisting that his GOP rivals and reporters interrogate him about it.

According to Pete Teeley, his campaign communications director, the vice president concluded while in Iowa last week "he has to answer everything on this, that there isn't anything new that can be asked, there isn't a question here that I have to worry about."

Bush simply gave the same answers he had before, but appeared to be more open and willing to respond, several aides said.

Teeley said Bush adopted this approach as he prepared to face the other Republicans at The Des Moines Register's debate Friday night. That morning, The Register printed on its opinion page a long chronology of known details about Bush's involvement but concluded that his role was "one of the episode's enduring mysteries." The day before, The Washington Post had reported that Bush watched the Iran arms deals unfold step-by-step in part through his presence at key meetings.

Privately, Bush was angry about the news reports. On the day of the debate he brought it up several times with aides as they flew to Springfield, Ill., for a quick campaign foray. Bush went to the debate that night prepared to scrap the entire format and tackle whatever questions came his way, according to another adviser.

"He was going to shift the burden to the inquisitors and abandon the format and let them exhaust their questions. It turned out they didn't have many questions," said the adviser. "It is clear that issues don't move Iowa voters -- they are much more interested in personal style. This approach actually helps."

Opening a second front, Bush then raised the issue of disclosing tax returns, which was implicitly directed at Dole. The senator at first said he didn't have to do what Bush demanded; yesterday he said he had always made summaries available and would release his returns "in due time, yes."

"I think we'll maybe want to go back 20 years," Dole said. "Why stop at 10? Why not go back from the day we were born?"

Dole was also questioned yesterday about the report in The Hutchinson (Kan.) News that a former aide, John Palmer, was involved in a financial transaction with Elizabeth Dole's blind trust and subsequently received a no-bid contract from the Small Business Administration to supply food service at Army mess halls at Ft. Leonard Wood, Mo.

The article said questions remain about real estate transactions involving Palmer and the blind trust. Dole yesterday acknowledged helping Palmer get the SBA contract but said, "I don't know anything about the blind trust."