US President Donald Trump aimed to make inroads Saturday in the politically important Jewish-American vote with a Florida speech where he declared himself the best friend Israel has ever had.

At a conference in Hollywood, Florida, the Republican real estate magnate said Jewish-Americans had been wrong to vote for Democrats under his predecessor Barack Obama.

"So many of you voted for people in the last administration," he said.

"Someday you'll have to explain that to me because I don't think they liked Israel too much."

By contrast, Trump said, "the Jewish state has never had a better friend in the White House than your president, Donald J. Trump."

Will Smith still feels "emotional" about homelessness years after playing a destitute man in one of his most acclaimed film roles, the Hollywood star has told charity campaigners braving a fierce New York winter night to sleep rough.

Hundreds of people had gathered in Times Square on Saturday, rugged up and ready to bunk down in freezing temperatures, in a campaign to raise funds for what organizers said was record homelessness globally.

Smith told the crowd that his Oscar-nominated role in "The Pursuit of Happyness" -- a 2007 biopic of a salesman forced to live on the streets of San Francisco with his young son -- was a "life-changing experience" that had allowed him to understand the misery of poverty.