President Donald Trump “has a hard time pushing back” against Vladimir Putin — and should “look at the Reagan playbook” to economically isolate Russia, Sen. Lindsey Graham said Sunday.

In an interview on “Fox News Sunday,” the South Carolina Republican said “the problem is that Russia is running wild.”

“Whatever we are doing is not working and the president for some reason has a hard time pushing back against Putin directly,” Graham said, adding: “They have an oil and gas economy. They couldn't survive very long without customers. If I were President Trump, Germany and Europe, France, I would try to cut off all of their customers and provide alternatives to their customers for oil and gas outside of Russia.”

Graham also touted national security adviser John Bolton ahead of Trump’s planned meeting with North Korean leader Kim Jong Un, who is coming to the table because economic sanctions have “hurt so much” and because Trump has called out Kim “for being the tyrant he is.”

“We've got an opportunity historic in nature to sit down and maybe not only get him to give up his nuclear weapons but to end the Korean war, which is still going on,” he said. “I would be very cautious about the terms and conditions of this meeting and this is why I like John Bolton as national security advisor. … He has a very healthy skepticism.”

Graham also asserted Trump’s announcement of his decision to pull out 2,000 troops from Syria would be “the single worst decision the president could make.”

"This is the Obama playbook — one foot in, one foot out,” Graham said. “This is a disaster in the making. All of his military advisers have said we need to leave troops in Syria to work with them, calm down the conflict between Turkey and the Kurdish fighters who have helped make sure that it does not fall back into the hands of ISIS."

“If we withdrew our troops anytime soon, ISIS would come back,” he said.