Donald Trump has a message for anyone who agrees to do a job for him: If I don't like your work or I think you're trying to rip me off, don't expect to be paid in full.

The billionaire front-runner to be the Republican candidate in the U.S. presidential race says he sometimes refuses to pay bills from contractors he has hired and then forces them to negotiate the final figure down.

"I've had many people that when they work for me they get very rich," Trump said in an interview, but, "sometimes I renegotiate." Adding: "I'll do that with probably 10 or 15 percent of contractors."