The latest national poll shows Donald Trump extending his lead over the rest of the GOP field in the race for president.

Merchandise of GOP presidential front-runner Donald Trump is for sale at Trump Tower on September 3, 2015 in New York City. (Photo by Spencer Platt/Getty Images)

According to Thursday's Monmouth University poll, support for Trump is now at 30 percent.

Jeb Bush fell four points and Scott Walker is down eight. Gov. Chris Christie remains at 2 percent, which puts him in a tie for ninth place.

In head to head matchups, Trump beats every single candidate running except for Dr. Ben Carson. Neither has ever held elected office.