"F-k Trump!" de Niro said.
Robert also said: "In these perilous times, you rock the vote, always fighting for truth, transparency and integrity in government. Boy, do we need that now!"
However, it was heard by those in the audience and journalists covering the awards show, which honors the best of Broadway theatre, and it quickly became the top trending item on Twitter.
The live audience seemed to feel the same way as they gave him a standing ovation.
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Tales of Vesperia: Definitive Edition does not now have a release date , though it is scheduled for a winter 2018 launch window. A power struggle begins in a civilization dependent on an ancient technology, the blastia, and the Empire that controls it.
De Niro said, "Do you have any idea how hard it is to get tickets for Bruce Springsteen's show on Broadway?"
Warning: this video contains strong language that some viewers may find inappropriate for offensive.
The White House did not immediately return a request for comment.
It's the latest-and certainly the most explicit-example of an entertainer using the microphone at an awards ceremony to express derision for Trump.
Among the Tony Award winners and performers at the show, members of the drama department at Marjory Stoneman Douglas High School, survivors of a school shooting in Parkland, Florida, that killed 17 people, brought the crowd to their feet with a rendition of "Seasons of Love" from "Rent".