NEW YORK, SEPT. 9 -- Gov. Mario M. Cuomo (D) said again today he is not a presidential candidate. To be sure, he is about to embark on a foreign policy foray to the Soviet Union; he has given several foreign policy speeches; he is pushing for a bipartisan commission on trade and deficit problems, and he has strong opinions on a number of national issues.

If reporters find in this pattern a prototypical case study of "Candidate Broadening His Resume in Preparation for a Presidential Race," Cuomo said that is their problem.

Cuomo had lunch today with two other Democratic noncandidates, former Colorado senator Gary Hart and Arkansas Gov. Bill Clinton, at which Cuomo sought advice on his trip to the Soviet Union, although Clinton said there was some political talk as well. Cuomo leaves for Moscow Sept. 19 for a week-long visit.

After returning to the fund-raising circuit last month, Cuomo hosted a conference on Soviet-American relations at which he called for "a new realism" in superpower relations.

Cuomo also plans to meet with Vice President Bush to discuss the governor's push for a national economic commission to advise the next president on trade and budget problems.

In the midst of this, no less an authority than Richard M. Nixon declared Cuomo the most likely 1988 Democratic presidential nominee. (Bush is Nixon's prediction on the GOP side.)

Cuomo recognizes that his trip to Moscow -- his first -- will fuel the very speculation he has tried to dampen. "Every reporter will make an interpretation, 'Of course, this fits neatly into a pattern if he wants to run for president,' " Cuomo said in an interview this week.

Although he began insisting in 1984 that he wasn't plotting a White House bid, Cuomo said, "People didn't believe me. They still don't. But I don't care. I said the heck with it."

A key adviser said Cuomo "intends to be more vocal on international affairs, particularly Soviet-American relations. In the past, he has been reluctant to speak out because it would be perceived as a platform in running for president. But now he doesn't feel like he has to pass a litmus test" to prove his noncandidacy.

Some continue to sketch a scenario in which Cuomo can run without running, saying that if the Democratic field remains splintered after the early contests next year, Cuomo could steal the prize with a late-starting campaign or prevail at a brokered nominating convention.

Cuomo was so frustrated by this speculation, sources said, that he flirted with the idea of endorsing Massachusetts Gov. Michael S. Dukakis (D). Cuomo said he believes that efforts to cast him as one of the few Democrats of national stature have the effect of denigrating the declared candidates.

"All they're lacking -- not competence, not integrity -- is celebrity," Cuomo said.

Cuomo said he plans to make an endorsement next February or March. But he dismissed suggestions that he is leaning toward Dukakis, sugggestions that were amplified when Cuomo's fund-raiser and former chief of staff, Michael del Giudice, joined the Dukakis campaign.

"I know him, I like him, we're colleagues, and I encouraged him to run," Cuomo said of Dukakis. "But there are a lot of unanswered questions. Mike is going to have to talk about how to close the deficit."

Political consultant Bill Cunningham, a former Cuomo aide, said "speculation will increase" about Cuomo's intentions during the Moscow trip, but that "almost everything he does revives speculation." He said he takes Cuomo at his word and cited a slogan used to promote the New York lottery: "You gotta be in it to win it."

Cuomo called the Soviet trip "a wonderful opportunity . . . . I believe the major issue for us at the moment is peace and survival, not to mention the expenditure of $15 trillion {on defense} in 40 years, just by the USSR and us."

Cuomo also has been seeking advice on the Soviet trip from former secretaries of state Henry A. Kissinger and Cyrus Vance. He did not ask for a meeting with Soviet leader Mikhail Gorbachev or other top officials.

As for his plan for a bipartisan economic commission, Cuomo said it would include members of Congress and would give the next president a detailed series of options after the 1988 elections.

"The next president is going to need a plan," Cuomo said. "The next president will not get such a plan out of the campaign. You can't do it in 28 seconds."