A federal jury yesterday was asked to see Michael K. Deaver's dramatic fall from power as either the tale of a Reagan administration insider anxious to trade on his position for millions of dollars in lobbying fees or the story of a dedicated but seriously ill Reagan loyalist reluctant to leave the side of the president he admired.

Those were the conflicting portraits painted of the former White House deputy chief of staff as his trial began in U.S. District Court here on five counts of lying to a congressional subcommittee and a federal grand jury.

Whitney North Seymour Jr., the independent counsel prosecuting the case, told the jury that this a case of a longtime aide to President and Nancy Reagan who "decided to turn that relationship into personal gain" and then attempted to cover up the contacts he made as a lobbyist, partly in fear of embarrassing the Reagans.

As he ticked off a list of Deaver's lobbying clients and stressed the large fees they paid him immediately after he left the White House in 1985, Seymour asked what he called "a critical question you're going to have to ask yourselves: 'Why? What were they buying?' "

Deaver's lawyer, Herbert J. Miller Jr., disputed those assertions in his opening arguments, saying that the case against his client was "a damnable lie," and that lobbying, "a perfectly honorable and legitimate business," was not on trial. Deaver, he said, was being hounded by a prosecutor intent on making a case out of a handful of answers the former Reagan aide made among more than 1,050 answers given in 11 hours of congressional and grand jury testimony.

"Let me explain what this case is not about," he told the jury. "It is not about political corruption. It is not about influence-peddling. It is not about making a lot of money."

The issue, both Miller and Seymour agreed, is whether Deaver "willfully" lied when he said under oath that he could not recall certain contacts he made with high Reagan administration officials on behalf of his lobbying clients.

Miller said Deaver was lucky to be in court at all, describing the former official's 1985 admission to Georgetown University Hospital for kidney failure as a life-threatening condition that resulted, briefly, in some "mental aberrations."

Deaver, he said repeatedly, was "not that kind of man" who would attempt to trade on his close relationship to the president. "If he was going to trade on that kind of relationship, he did not have to deal with those kind of people," Miller said. " . . . He would have just called the president of the United States."

The prosecutor maintained, however, that Deaver was attempting to cash in on his relationship, and that at one time a contract to sell his then-flourishing lobbying business for upwards of $16 million seemed within his grasp. But then, drawn to the case by the publicity over Deaver's booming business, the investigators began focusing on Deaver's clients, and the deal fell through, Seymour said.

In the style of a headmaster lecturing his students, the Park Avenue lawyer, one of seven special prosecutors assigned to handle allegations of high corruption in the Reagan administration, laid out in simple terms the five-count indictment that could send Deaver to prison for 25 years, relating the offenses to Deaver's clients.

Boeing Co., the aircraft maker, wanted to sell the White House a new $200 million Air Force One; Canada wanted U.S. action on acid rain pollution; Rockwell International Corp. wanted to build a space station; Trans World Airlines wanted to stop a hostile corporate takeover, and Puerto Rico wanted to retain a tax break for its industries.

Deaver obliged his clients with telephone calls and brief conversations with top Reagan administration officials -- Secretary of State George P. Shultz, then-Transportation Secretary Elizabeth Hanford Dole, then-national security adviser Robert C. McFarlane and Treasury Secretary James A. Baker III, the prosecutor charged.

And when problems surfaced, such as when an aide to Vice President Bush was reluctant to approve a paragraph in a Bush speech endorsing the Puerto Rican tax break, there was Craig Fuller, a Deaver friend and Bush's chief of staff, to put a slightly modified paragraph into the speech.

If Seymour was somewhat pedantic with a nearly two-hour opening statement delivered without notes, Miller attempted to evoke a more folksy image, crossing his arms at times and speaking much more briefly to the jury.

Deaver, he said, was a Reagan loyalist who had worked his way through college playing the piano and first served Reagan when he was governor of California.

Deaver testified "truthfully as far as he could remember," Miller said, adding that "there is another thing" that may have affected his memory.

"His drinking problem had gotten out of hand," Miller said, saying that the pressures of Deaver's White House job were forcing him to neglect his family.

His lobbyist fees "may sound high to you and me, but in Washington they are normal," Miller said.

This image of Deaver appeared to have been enhanced by the first prosecution witness, James Lake, a former Reagan aide from California and a Washington lobbyist.

Lake testified that he had urged Deaver to leave the White House as early as 1982 and go into business "and establish himself" doing for private business what he had done for Reagan.

Deaver, he said, knew how to use the news media to create "the perception" the American public has of the president.

"In my view, Ronald Reagan would not be president today without the advice of Michael Deaver," Lake said.

The trial is expected to last three to five weeks.