Days after Rudy Giuliani scolded Donald Trump for going off-script, the former New York City mayor is back on board the Trump train.

Giuliani applauded Trump on Fox News Monday night for the ideas the billionaire businessman outlined in his economic speech earlier in the day.

"The whole economic program is a comprehensive one. It's one that works. It's one that's proven. It's what Reagan did. It's what Kennedy did. It's what I did, in New York City, but on a smaller scale," Giuliani told host Greta Van Susteren. "Maybe Donald Trump has become as politically savvy as Ronald Reagan."

The Trump surrogate argued his 2016 pick changed minds within the Republican Party after his address, but said he will not win over Washington insiders within the GOP.