The bitter campaign for the GOP presidential nomination moved from Iowa to the floor of the Senate yesterday where an angry Sen. Robert J. Dole (R-Kan.) twice personally confronted Vice President Bush over charges made by Bush's Iowa campaign chairman that the senator's career showed a pattern of "mean-spiritedness" and "cronyism."

The unusual double exchange of words on the Senate floor, during a procedural vote on aid to the Nicaraguan contras, was the fourth time in less than a day that Dole, described by aides as "steaming mad" over the charges, has demanded Bush disavow statements of his Iowa chairman and apologize.

The senator, in a news conference between the two confrontations, accused Bush of "groveling in the mud" and charged that the Bush campaign was involved in publicizing a House committee staff investigation into the awarding of a controversial government contract to a former Dole aide. Bush spokesman Peter Teeley denied that allegation, and Bush's campaign director, Lee Atwater, said, "Yesterday, the Dole campaign was blaming The Washington Post and the Democratic Party. Now they have thrown us into the mix. The fact of the matter is this campaign had nothing to do with any of this."

The Bush campaign's charges of cronyism by Dole came a day after the staff of the House Small Business Committee issued a preliminary report in which it cited numerous "appearances of improper activities" in the $26 million Army contract, which Dole's office worked to help a former aide, John Palmer, obtain through the Small Business Administration (SBA).

The committee recommended that the Justice Department investigate it. Dole has denied any direct involvement, but a former SBA official this week said he had

been told the senator had made at least one phone call on behalf of Palmer.

The latest series of personal exchanges come in a GOP nomination battle that started with personal barbs as the campaign year opened, but settled down somewhat after the two leading candidates agreed to a truce. With only days before the Iowa caucuses open the voting on Monday, the truce has evaporated.

Both Republicans were in Iowa in the morning, but dropped their campaigning to fly back to Washington yesterday for a Senate vote on contra aid before returning to Iowa.

The first Dole-Bush exchange, which lasted only a few minutes, came when a visibly angry Dole strode up to Bush, who was in the presiding officer's seat in the Senate in mid-afternoon. Neither Dole nor Bush could be heard in the galleries, but Dole could be seen waving a copy of a statement by Bush's Iowa chairman, George Wittgraf, and observers said he appeared to be jabbing his finger at the statement and lecturing Bush.

The statement, which said Dole "virtually brought down" the 1976 GOP ticket when Dole was the vice presidential candidate, also cited news articles about the contract, and articles about controversies surrounding the blind trust of Dole and his wife, as well as other aspects of Dole's career.

Dole told reporters later that the Wittgraf news release was "one of the nastiest things I've seen in politics." He said he decided to confront Bush "man to man" about it.

The vice president, Dole said at his news conference, "authorized this release. He can't deny it. He can't run away from it. He can't say he has taken the high ground."

Dole then referred to a second Wittgraf statement yesterday that essentially repeated the charge of cronyism. Dole called it "low-down, nasty, mean politics. . . . I understand politics is tough. But not this nasty, this mean, this personal, this vindictive. I understand politics, and I understand when it is below the belt."

Dole vowed to confront Bush later with the second press release and did so in the midst of the late-evening vote. A grim-faced Dole walked up to Bush, who was again seated in the presiding officer's chair, and shook a piece of paper, presumably the press release, at Bush as he talked. Reporters seated in the gallery could see the short exchange but not hear it.

Aides to Bush said the vice president described the initial Senate floor exchange as short, beginning with Dole "coming up and waving this thing in his face." Bush told his aides Dole had demanded that he disavow the press release, and that the vice president declined, saying Dole had made "eight pages' worth" of attacks on him that had angered Wittgraf, who had replied.

Bush aides said the vice president had not seen or read the statements before they were released, but was told by Wittgraf that he intended to issue them because he was angry at Dole's attacks on Bush and other Republicans. Said Atwater, "Sen. Dole seems to be good at dishing it out, but like a schoolyard bully, he has a hard time taking it."

Dole has been angry about the original Wittgraf statement ever since reporters showed it to him when he arrived at an Iowa campaign stop Wednesday.

Even before he confronted Bush here, Dole attacked Bush's "last-minute desperation tactics" in a speech at the Osage, Iowa, Knights of Columbus Hall.

In charging the Bush campaign with being behind publicity over the staff committee probe, Dole attempted to discredit Robert Lhulier, former chief of staff to then-SBA Administrator James C. Sanders. He said Lhulier, who reported the alleged phone call from Dole to Sanders, got his job through a congressional Bush supporter and had contributed to the Bush campaign. Dole also released a statement noting that one of Lhulier's friends, and his predecessor in the SBA job, is married to an aide to Bush's chief of staff, Craig L. Fuller. Lhulier could not be reached for comment.

Staff writers Anne Swardson, David Hoffman and Bill Peterson contributed to this report.