Billionaire Donald Trump is blowing away his nearest competitor, Wisconsin Gov. Scott Walker, 2-to-1, in a poll of Iowa Republican voters released Friday by Gravis Marketing on behalf of One American News Network.

Trump has a 15-point lead over Walker in the poll taken of 227 registered Republican voters in the Hawkeye State, asked Wednesday who among the GOP candidates for president they would vote for if the caucus were held today.

The results, according to the poll:

Trump, 30.9 percent

Walker, 15.4 percent

Former Florida Gov. Jeb Bush, 10 percent

Louisiana Gov. Bobby Jindal, 7.2 percent

Former Arkansas Gov. Mike Huckabee, 6 percent

Texas Sen.Ted Cruz, 5.5 percent

Retired neurosurgeon Ben Carson, 5.1 percent

Ohio Gov. John Kasich, 5 percent

Former Hewlett-Packard CEO Carly Fiorina, 4.3 percent

Former Pennsylvania Sen. Rick Santorum, 2.9 percent

Florida Sen. Marco Rubio, 2.8 percentFormer Texas Gov. Rick Perry, 1.7 percent

South Carolina Sen. Lindsey Graham, 1 percent

Source: Iowa Poll: Trump Takes Huge Lead Over Walker