At the baronial Morgan Library in Midtown Manhattan the other night, President Mahmoud Abbas, the Palestinian leader, stood quietly along the edge of a diplomatic reception, avoiding the animated gossip and flowing Champagne.

Only when the host noted that Mr. Abbas was in the room, and expressed hope that his quest for Palestinian membership in the United Nations would produce real sovereignty, did the crowd take notice.

For decades, the defiant, charismatic and unpredictable Yasir Arafat, always in military uniform, needed no introduction. Seven years after Mr. Arafat’s death, Mr. Abbas, a gray man of sober suits and sensible shoes, may now be slowly emerging from his shadow.

In bringing his cause to the United Nations despite intense American pressure, Mr. Abbas has captivated the annual General Assembly gathering, bolstered the flagging devotion of his people and even cornered his rivals in Hamas. The question is whether this moment of unparalleled prestige for the Palestinian leader will produce concrete results or a new and more dangerous set of risks.

Here in New York, leaders are lining up to meet with Mr. Abbas, the central protagonist in the session’s chief drama. In the West Bank and Gaza, Palestinians are offering rare praise for a leader who has mostly been seen as Hamlet-like in his indecision, trying too hard to please the Americans and the Israelis.

“We never thought of him as having his finger on the pulse of the Palestinian people the way Arafat did,” said Sandra Tannouf, a 17-year-old student at a West Bank rally supporting the United Nations move. “He never filled the gap left by him, but I fully support this step. Maybe we will get our country back.”

Ms. Tannouf was standing among tens of thousands of fellow supporters, Palestinian flags fluttering, bands playing, and banners of Mr. Arafat and Mr. Abbas covering the sides of buildings.

Schools, universities and ministries closed early to assure a crowd, but an opinion survey released on Wednesday showed that may have been unnecessary; more than 80 percent of the population is behind the move. Mr. Abbas is also comfortably outpolling his Hamas rival in both the West Bank and Gaza.

The same survey, however, suggests why many Western diplomats fear the good feelings cannot last. Asked what should happen after a United Nations vote, three quarters of Palestinians said they should impose their sovereignty over the West Bank, even if it leads to confrontations with Israeli soldiers and settlers.

Mr. Abbas says the opposite — the United Nations move is not a substitute to negotiations with Israel but a prelude to more of them.

“For three-quarters of the public, going to the United Nations is about exercising sovereignty,” Khalil Shikaki, a political scientist and the director of the opinion survey, said by telephone. “He is a hero for this. But he doesn’t evoke emotions, he is not a great communicator and he lacks charisma. The people simply support his policy. The problem is that there is a disconnect between what he wants and what the public wants. And that could come back to haunt him.”

Rana Baker, a 20-year-old student in Gaza City, showed how that disconnect is functioning.

“There is only one good thing in the bid for the U.N.,” she said. “Abbas has finally understood that negotiations are useless. I’m against the two-state solution because it gives us some 22 percent of Palestine’s land and that state would be cut by settlements.”

Mr. Abbas, 76, has repeatedly expressed a desire to retire from public life, and he is widely thought to be focused less on the next step than on his legacy. That may be partly what persuaded him to appeal to the United Nations. Fruitless negotiations with Israel made him feel as if he had little choice — and little to lose — by taking his case to the sympathetic world forum.

At times recently, this moody, brooding man seems to have found a kind of liberation, evident in a spring in his step, in deciding to defy Washington and force his people’s plight into international consciousness. He has displayed humor. At other times, however, he has seemed utterly lonely.

He took umbrage on Tuesday night at the Morgan Library when asked if he had taken an uncharacteristically confrontational approach.

“Confrontational step? How?” he asked. “I am confronting whom? I am not confronting anybody. I am talking openly to everybody that I want peace.”

Shimon Peres, Israel’s president, met secretly with Mr. Abbas three times in recent months in efforts to bridge the gaps between the Palestinians and the Israeli government of Prime Minister Benjamin Netanyahu and avoid a United Nations battle. Mr. Netanyahu ultimately pulled the plug on those talks, leaving Mr. Abbas a sense of having no alternatives.

Mr. Peres said in an interview in Jerusalem that he tried to convince Mr. Abbas that United Nations membership would not help because what is needed is independence for the Palestinians and security for the Israelis, and the United Nations can deliver neither.

“He told me, ‘I’m alone, betrayed by the United States, betrayed by Israel and by everyone else,’ ” Mr. Peres recalled from a recent conversation.

Mr. Abbas echoed those sentiments on Tuesday night. Terje Roed-Larsen, a former United Nations envoy to the Mideast who now leads the International Peace Institute in New York, hugged him and asked for a meeting later in the evening.

“Tonight our schedule is full with the Americans,” Mr. Abbas replied. “They want us to meet, but we don’t, really we don’t want.”

Mr. Larsen asked why he was going then. “I don’t know why really,” Mr. Abbas said, “I am not happy with anybody, not with the Americans, nor the Arabs. I am fed up with all these people and I don’t know what to do when I return back.”

Mr. Abbas has worked hard to counter Hamas’s focus on resistance and instill a political culture of nonviolence among Palestinians after the bloody uprising that began in late 2000. Normality, with a strong security force and developing economy, has started to set in. Mr. Shikaki, the pollster, said that Mr. Abbas arrived at a time when the public was fatigued with violence “so his message fell on fertile ground.” He added that the recent events in Tahrir Square in Cairo also inspired Palestinians.

“The majority believes that if there are peaceful demonstrations, even nonconfrontational ones, this will speed up an ending to the occupation,” he said. “In 20 years, I have never seen that much confidence in the efficacy of nonviolence. I would give him some credit for that change.”

He added that the big concern remained what happens after a United Nations vote, likely to take place in the coming weeks. If, some months later, nothing has changed on the ground, not only is Mr. Abbas likely to lose his popularity but frustration could also lead to violence and Hamas may be the beneficiary.