The third debate ahead of the November 8 election was marked by Republican Trump's refusal to commit to accepting the outcome of the election if he loses to his Democratic rival, challenging a cornerstone of American democracy.
The dinner, named after the former NY governor and first Catholic to lead a major-party presidential ticket, came a day after a brutal third and final debate between the candidates.
Asked at the debate whether he would accept the outcome, Mr Trump said: "I will tell you at the time".
"And I very politely replied, 'Let me talk to you about that after I get into office, '" said Trump, a Republican whose supporters chant "lock her up" at rallies.
"Donald looks at the Statue of Liberty and see a four, maybe a five if she loses the torch and tablet and changes her hair", Clinton said.
Thursday, he spoke about those comments saying he would accept the outcome of the presidential election if he won.
"I feel at this point in our country's history, that it is important that we not reverse marriage equality, that we not reverse Roe v Wade. that we stand up and basically say "The Supreme Court should represent all of us". He said that Michelle Obama gave a speech "and everyone loves it".
Another Republican senator, Bob Corker, who has campaigned with Trump, tweeted: "It is imperative that Donald Trump clearly state that he will accept the results".
"I certainly expect that the dinner will be what it's always been: an opportunity for two candidates to put aside partisan politics for the evening", said Joseph Zwilling, the spokesman for the Archdiocese of NY, which hosts the dinner. They think she's so great.
He brushed off the likelihood of that happening, confident predicting that "we're not going to lose".
Trump kicked off the sledging with jokes about Clinton's email controversy.Trump took aim at Clinton for most of his speech but also joked about his wife's speech failure.
Donald Trump said Thursday he will accept the results of next month's election if he wins, a caveat that threatens to cast unprecedented doubt on the legitimacy of the electoral process. The GOP's top concern was turning to salvaging its majority in the Senate, followed closely by worries over the Republicans' once comfortable grip on the House.
Republican presidential nominee Donald Trump speaks during a rally at the Delaware County Fair in Delaware, Ohio.
Smith also teased Clinton, noting that "titans of Wall Street" were in attendance, but told her to restrain herself from seeking donations and to "remember the children". He cited a hacked e-mail that showed she was tipped about a death penalty question during a primary season town hall. "How corrupt do you have to be to get kicked off the Watergate Commission?" "Then you are doing the work of our adversaries for them", he said.