PITTSBURGH, NOV. 23 -- Intentionally or not, New York Gov. Mario M. Cuomo (D) is mucking things up for the six men who want the prize he refuses to seek openly, the Democratic nomination for president.

So say a growing collection of Democratic Party leaders, for whom the Cuomo conundrum -- Is he or isn't he really running? -- has worn thin.

"The candidates are like characters in a play where the audience keeps getting diverted by a shadow from off stage," said Ann F. Lewis, former political director of the Democratic National Committee. As a result, she added, "I can't recall an election where so many activists were staying so uncommitted so late into the process."

Cuomo adamantly denies he is positioning himself for a late entry or a convention draft, but he and his peripatetic shadow were on the road again tonight -- this time delivering the keynote speech at a fund-raiser to help Pennsylvania Gov. Robert Casey retire his 1986 campaign debt.

Sixteen hundred party faithful -- a record for a Democratic fund-raiser in this city -- turned out to hear Cuomo deliver his familiar ode to the politics of inclusion and his attack on the Republican ethic that "God helps those whom God has already helped."

He was interrupted more than a dozen times by applause, but a hoped-for draft-Cuomo demonstration never materialized -- in part because its instigator, Pittsburgh businessman Meyer Berger, bowed to the requests of the Pennsylvania and New York state party chairmen that he not stage one.

Still, there was plenty of sentiment in the room for Cuomo. "He's the salvation of the Democratic Party," said Tony Pokora, a local ward leader who was sporting a Cuomo-for-president button. "The others are all so blase."

Cuomo disagreed. At a press conference before his speech, he called the candidates, "the best ever assembled by the Democratic Party," and reiterated his intention not to join it. He said the only reason there was interest in him was that "we're in a vacuum period right now, everything will change after Iowa." But whether it is merely the restiveness of the season, or something deeper, nationwide polls this fall show widespread voter disaffection with the Democratic field and a strong desire for Cuomo to get in.

A Peter Hart survey taken for the Chicago Tribune last month of 1,501 voters in five large states showed that 55 percent of Democrats polled wanted someone else in the race. The same survey, taken of Democrats, Republicans and independents alike, showed Cuomo to be as popular as President Reagan and more popular than any of the 12 candidates. Fifty-two percent of those polled expressed positive feelings toward him, compared to 23 percent who had negative feelings.

A Field poll taken of California Democrats earlier this month also showed Cuomo at the top -- with 49 percent saying they would be "inclined" to vote for him, compared to 12 percent who said they were disinclined. Jesse L. Jackson was the only other Democrat to have more than a third saying they were favorably inclined.

Cuomo's popularity, and his refusal to hide his light under a bushel, has begun to irritate some of the active candidates -- though most are too diplomatic to say so publicly. Jackson is the exception. "He's running in a place where there are no blockers and tacklers," he said in an interview. "If I get beaten, I want it to be by someone who's on the playing field."

Sen. Paul Simon (D-Ill.) took the opposite tack. At a Cuomo-hosted breakfast in New York last week, Simon said the governor was "superbly" qualifed for any government position and urged him to continue speaking out because "we need your leadership."

Not everyone is quite so effusive. "You're starting to hear some resentment," said Paul McEachern, Democratic candidate for governor in New Hampshire. "Myself, I think he's doing a disservice to the party and the process. What good does it do us for someone to come in late, grab the nomination and let us discover the warts afterwards."

McEachern touched on one of the most popular political parlor games of the season -- speculating on whether a late candidacy is possible under Democratic Party rules, much less advisable.

While possible, that move would require an unprecedented chain of events. On the other hand, there are already several circumstances in place that make the 1988 contest unusually fertile for a late entrant.

The "front-loaded calendar" of primaries means that for the first time ever, half the delegates will be chosen within the first five weeks of voting -- from Feb. 8 to March 15 -- at a time when both the field and the potential for diffusion of the vote will be its largest.

Moreover, the absence of an early frontrunner and the fact that the Republican primaries and caucuses will be sharing -- perhaps dominating -- the February political headlines increase the chance that no Democratic candidate will break out of the "gate states" of Iowa and New Hampshire with a decisive media mandate.

It's not inconceivable that three or four candidates might still be alive going into Super Tuesday, March 8: The winners of Iowa and New Hampshire (they could well be different people), Jackson, whose black base is secure, and Sen. Albert Gore Jr. (Tenn.), who is positioning himself to jumpstart his campaign on that date, when 14 Southern and border states go to the polls.

Most students of the process, and of Cuomo, believe that the period immediately after March 8 is the earliest he could reverse himself and declare his availability -- and then only if the vote, indeed, had been split up and the prospect of a brokered convention loomed.

At that point, it would be too late for Cuomo to get onto the ballot in all but 13 late primares and caucuses -- too late, for example, to get his name on the ballot or file delegates for the Illinois primary on March 15, the New York primary on April 19, or the Pennsylvania primary on April 26.

Cuomo could still file for the June 7 primaries in California (filing deadline, March 24) and New Jersey (deadline, April 13). He could also compete for Democratic House and Senate members -- 80 percent of whom are guaranteed spots at the convention as unpledged delegates. They will be chosen in late April, and could be in a position to "validate" a late Cuomo candidacy with leadership support.

Cuomo could also compete for the 363 members of the Democratic National Committee, all of whom will be convention delegates and at least two-thirds of whom remain uncommitted, according to most estimates. And he could make a bid for the support of the AFL-CIO which has not yet endorsed anyone and, in the absence of the emergence of a clear frontrunner, will not.

The overall game plan of any late entering candidacy would be to accumulate preconvention support and then start to woo the delegates pledged to others. By party rule, none of the 4,158 delegates are legally bound to any candidate on any ballot. In practice, however, the delegates are extremely loyal to their candidates and could only be pried lose if there were no chance their candidate could win.

Some of those who know Cuomo say the private misgivings he had about the presidency when he took himself out of the running last February have been largely swept away by time and circumstance. They think he would now love to find a pretext to get in, and that he's frustrated by the political box he built for himself. That's why, they say, he spends so much time on the road and the telephone -- stirring the pot by protesting too much his noncandidacy.

Others disagree. "If he wanted it, he wouldn't put himself in a situation where to get it, others would have to fail," said Brad Johnson, head of Cuomo's New York state Washington office. "He is not someone who likes putting his destiny in other people's hands."

Former Democratic chairman Robert Strauss concurred. "He woundn't be as cute as he's being if he wanted to run," he said.