“He’s the presumptive nominee. Now the party is going to have to unify around someone that they did not expect to be the nominee,” Quayle said on NBC News’ TODAY. “I was a Republican vice president, I’ve been a Republican all my life, I’m going to support the nominee.”

Quayle’s backing gives Trump a notable establishment voice at a time when he is struggling to win over the Republican Party.

Trump has exposed deep divides in the GOP, and leading voices have said they are not prepared to support him, citing his positions as well as his brash political style.

The president during Quayle’s tenure in the White House, George H.W. Bush, as well as former president George W. Bush have stayed on the sidelines, while prominent Republicans such as South Carolina Sen. Lindsey Graham and Florida Sen. Marco Rubio have declined to support him.

Trump will meet on Thursday with House Speaker Paul Ryan, who has said that he is not ready to back him.

Quayle said he expects Ryan to unify behind Trump. “I fully expect that Paul Ryan will eventually support Donald Trump publicly,” he said. “We do have to be unified. If we’re not unified we have a real lot of trouble.”

Quayle recommended Ohio Sen. Rob Portman as Trump’s vice presidential pick and added that Trump needs to brush up on his policy chops.

“He really needs to get more involved in the policy,” Quayle said. “He made a speech on foreign policy. He’s got to make another speech on foreign policy, he’s got to make a speech on the economy, he’s got to show he’s presidential.”

This article was originally published on Time.com.