President Reagan tonight paid tribute to the memory of two Roman Catholic prelates, a Jewish philanthropist and a New York governor in a brief but emotional speech that avoided partisan rhetoric but sought to reinforce his standing with key political constituencies.

"All of them personify the great commandment -- to love our fellow man," Reagan said in remarks at the Alfred E. Smith Memorial Dinner.

The $300-a-plate dinner, begun by the late Cardinal Francis Spellman in 1945 to benefit Roman Catholic charities, was attended by 2,200 guests, including many notables from the Catholic archdiocese.

Reagan's political advisers, who were pleased that Democratic presidential nominee Walter F. Mondale rejected an invitation to attend, have targeted Catholic voters throughout the campaign and are counting on strong support from voters of Irish, Italian and Polish heritage, many of them Catholic and a majority of whom are Democrats.

A Washington Post-ABC News Poll on Wednesday showed Reagan with a 20-point lead among Catholic voters, far higher than his overall 12-point lead. Furthermore, his support among Catholics has remained consistent, despite his loss of ground after his Oct. 7 debate with Mondale.

Tonight, Reagan paid tribute to Smith, the 1928 Democratic presidential nominee who was defeated after a campaign marked by religious prejudice. Reagan referred to him as "the happy warrior whom time and respect and affectionate memory have elevated beyond partisanship."

Reagan also honored the memory of Spellman and his longtime dinner chairman Charles Silver, who Reagan said "raised millions for hospitals serving all faiths."

The other person honored by Reagan was Cardinal Terence Cooke, who died last year after a long illness. Reagan told an emotional story about how Cooke had visited him at the White House after Reagan was wounded in an assassination attempt and how he and his wife, Nancy, returned the visit as Cooke lay dying last year.

The Cooke visit to the White House on April 17, 1981, Good Friday, was the source of a comment that Reagan has since made to intimates about the attempt on his life by John W. Hinckley Jr. on March 30 of that year.

Though Reagan didn't relate it tonight, he said soon after the visit that Cooke told him, "The hand of God was upon you."

"I know, and whatever time He's left for me is His," Reagan said.

Reagan praised Cooke for his contributions to "international peace and justice" and said he had told Cooke in their last visit that he was "grateful for all the cardinal had done in behalf of his country."

Reagan concluded by saying that Cooke had died 11 days later and that "none of us have any doubt that he joined the Lord."

Archbishop John J. O'Connor, a friend of Reagan who presided over the dinner and introduced him, responded to Reagan's speech in a lighthearted fashion, saying Cooke had a different recollection of his last meeting with the president.

"He had no doubt he would be with the Lord," O'Connor said, looking straight at Reagan. "It was you he was worried about."

The dinner provoked a dispute earlier in the week when Mondale declined an invitation to appear, saying he had to prepare for Sunday's second debate. His aides said he wanted his running mate, Geraldine A. Ferraro, to substitute.

But David A. Werblin, the dinner toastmaster, said the sponsors never received a request from Mondale that he be represented by another speaker.

Mondale's name was greeted with a sprinkling of boos when Werblin read his letter declining the invitation. Reagan made a brief, joking reference to Mondale's absence.

A White House fact sheet distributed to reporters today said inaccurately that the dinner "traditionally attracted the Democratic and Republican nominees for president in every election since 1960 . . . . " Vice President Spiro T. Agnew appeared in place of President Richard M. Nixon in 1972.