Sen. Dennis DeConcini (D-Ariz.) yesterday challenged the motives and impartiality of Senate ethics committee special counsel Robert S. Bennett in an impassioned, defiant defense of his dealings with savings and loan executive Charles H. Keating Jr.

In response, Bennett angrily suggested that DeConcini was attacking him to divert attention from the facts in the "Keating Five" case.

DeConcini, making the final opening statement of the five senators who are being investigated by the panel for helping Keating fight federal regulators while he was raising money for the senators' campaigns and political causes, accused Bennett of "bias" and said he relied on "lies" and "hearsay" in reaching his conclusions.

Bennett acted like an overzealous "prosecutor" in trying to "nail somebody" and hang "another trophy on the wall" of his legal achievements, DeConcini told the panel in appealing to its members to disregard Bennett's conclusions.

In a preliminary report to the committee two months ago, Bennett recommended that the panel intensify its investigation of three of the senators -- Alan Cranston (D-Calif.), Donald W. Riegle Jr. (D-Mich.) and DeConcini -- but take no action against the other two, John Glenn (D-Ohio) and John McCain (R-Ariz.).

The committee is investigating whether there is a connection between the five senators' intervention on behalf of Keating's failing Lincoln Savings and Loan Association of Irvine, Calif., including two Capitol Hill meetings with regulators in April 1987, and the $1.3 million that Keating raised for their campaigns and causes during the same period. Keating is facing trial in California on junk-bond fraud charges. Lincoln's failure is expected to cost taxpayers at least $2 billion.

Like the other four, who made their opening statements Friday, DeConcini vigorously denied any improper conduct. "I broke no law, I broke no rule, I broke no standard, I committed no improper conduct," he said.

But he went far beyond any of the others in taking the offensive in stating his side of the case, including criticism of the lobbying group Common Cause, which he accused of bringing the original charges against the five senators to "raise money for their {own} salaries and to get more members."

DeConcini also suggested that McCain, his Arizona colleague and the only Republican in the group, had been treated more leniently than the others, saying there appeared to be a "kind of cozy" relationship between Bennett and McCain.

Asked by reporters afterward if he thought partisan motivation was a factor in Bennett's conduct, DeConcini said, "I would like to think it isn't." Bennett is the brother of William J. Bennett, the outgoing director of drug policy in the Bush administration who is in line to take over the chairmanship of the Republican National Committee.

In response, Bennett, who in his earlier presentation of the case identified DeConcini and Cranston as "important players" in Keating's "all-out war" with federal regulators on behalf of his failing thrift, asked the committee not to be "distracted" by DeConcini's counterattack.

"The issue in this case is not me," he said. "It is not Common Cause. The issue in this case is the conduct of the senators. That is what brought them here."

"And they know and I know that when you don't like the facts and when you don't like the law, you go after the opposing lawyer," Bennett continued. "And you know that when you don't like the message here on Capitol Hill, you burn the messenger."

In response to arguments by DeConcini and Cranston that he is attempting to judge them by ethical rules of his own making, Bennett said the standards are those of the Senate, approved by the ethics committee and followed by most senators. They include the official code of ethics for government services, which bans officials from accepting favors under circumstances that might be construed by reasonable persons as influencing the performance of their duties, he said.

They are no less specific, Bennett said, than standards governing military officers, judges, baseball players, staffs employed by senators and even the disciplinary standards for students at the school attended by his three daughters, Potomac School in Fairfax County.

The Senate cannot say "it's good enough for the rest of the world but not for the United States Senate," he said. The case may well determine "the respect and the confidence that the American people have in this institution," he added. "Because, unfortunately, in judging the past, you're going to be writing for the future."

But "the unfairest cut of all," Bennett said, was the suggestion Friday by Cranston that he had done nothing different from other senators who are authorized under Senate rules to designate staff members to accept campaign funds.

He cited a January 1987 memorandum to Cranston from outside fund-raiser Joy Jacobson who wrote that Keating was among supporters who "rightfully expect" some resolution of their pending requests for help. Bennett questioned whether he would find such memos in most other senators' files.

"I've been investigating this case for a year," Bennett said. "Everybody doesn't do it. . . . The one thing I've learned in my investigation in this year is this case is an aberration."

Challenging this notion, DeConcini said virtually every senator is at risk from similar ethics inquiries under the current system of campaign financing. "I wish I had kept a notebook of all the senators, including a couple on this committee, who have said, 'But for the grace of God, there go I, or you.' "

In defense of his actions, DeConcini said that when he first got to know Keating as an Arizona businessman and anti-pornography activist he "had a very good reputation" and was "a very different person than he is perceived today . . . a very, very generous person."

He cited a number of Keating's contributions to charitable causes, including $2 million to Covenant House, $1 million to the Little Sisters of the Poor and substantial gifts to Mother Teresa for her work with the poor. DeConcini said that when he met Mother Teresa in 1986 and told her he was from Arizona, "the first thing she said {was} 'How is my friend Charlie Keating?' "

Among the favors he did for Keating, he added, was to help a Catholic priest emigrate from Yugoslavia to the United States. "Is there some sin in helping a Catholic priest or a large businessman who wants to bring the priest into Arizona?"

DeConcini cited his efforts on behalf of constituents as a point of honor, contending he acts on their behalf regardless of whether they are campaign contributors. He said he pressed to continue production of Apache helicopters in Arizona by McDonnell Douglas, whose officials have contributed to his campaigns, but also intervened with the Immigration and Naturalization Service to help an Arizona couple bring an adopted Turkish orphan into the country, even though they were Republicans.

He denied Bennett's allegation that he tried to negotiate a relaxation of investment rules for the Lincoln thrift at the April 1987 meetings between the five senators and federal regulators. But, even if he had done so, it would not have been against the rules, DeConcini argued.

He also denied Bennett's suggestions that he continued trying to help Keating after learning that regulators were recommending a criminal investigation of Lincoln, saying he only made inquiries about the status of the case.

In regard to McCain, DeConcini said Bennett paid little if any attention to McCain's wife's investments with Keating or to Keating-financed trips that the McCain family took to the Bahamas, including one where they were joined by Lee Henkel, whom Keating was promoting for appointment to the Federal Home Loan Bank Board.

Staff writer Tom Kenworthy contributed to this report.