"I have a big heart," Trump said. Biden didn't agree.
The Democratic vice presidential nominee plans is scheduled to appear in his home town on Monday.
A formal announcement is expected to come out in the next several days.
The volley comes as Democrats coalesce around their new presidential nominee, Hillary Clinton.
The Clinton campaign has been trying for months to counter liberal suspicions that Clinton is not a true convert on TPP.
Clinton has formally won the Democratic presidential nomination, emerging from a long and bruising primary season to become the first woman to lead a major party in the race for the White House. This is a developing story. It will be updated.
"I think the ballroom and the people who own this hotel should be ashamed of themselves,” Trump said.
The $30,000 check came from an Atlantic City casino.
In his address, the Vermont senator again tossed his support behind Hillary Clinton.
The first lady got emotional at one point, talking about her two daughters.