A big day for Donald Trump.

The Republican Party presidential nominee has been running through his acceptance speech which he'll deliver to the Republican Convention late this morning.

USA Today Washington correspondent Paul Singer told Andrew Dickens we don't know yet whether he'll read a prepared text, which is never his best performance or whether he'll be the real live Donald some people love so much.

He said Donald Trump has plenty of material to work with.

"He can complain about the media making fun of his wife's speech, he can complain about the treatment by Ted Cruz, he can thumb his nose at the entire party establishment that doubted him."

Singer said it's hard to imagine Donald Trump standing there reading a speech that says 'Dear America, Let us all come together and unite for the future.'

LISTEN ABOVE: USA Today's Paul Singer speaks with Andrew Dickens

Ryan Lizza of The New Yorker said Mr Trump needs to convince not just those who fawn over him, but others as well, that he's fit to be President of the United States.

"So this is it for him. He's struggling to break 40 percent in the polls. If he doesn't come out of this convention having convinced a bigger chunk of the country outside of the people that come to this convention, he's in trouble."