Sen. Lindsey GrahamLindsey Olin GrahamCongress punts fight over Dreamers to March Pence tours Rio Grande between US and Mexico GOP looks for Plan B after failure of immigration measures MORE (R-S.C.) says that President Obama is "literally insane" for withdrawing troops from Afghanistan by 2017. 

"His decision to withdraw all of our troops by 2017 in Afghanistan is literally insane in light of Iraq," Graham said Tuesday night on Fox News's "On the Record with Greta Van Susteren." "All of his military commanders are saying you should not set a date for withdrawal, you should withdraw based on conditions."

Obama has kept around 10,800 troops in Afghanistan this year, even though the combat mission has technically ended, but all U.S. troops are scheduled to leave by the end of 2016. 

Graham, a leading foreign policy hawk who has floated a run for president, faults Obama for not leaving a residual force of troops in Iraq after 2011, and says the same mistake is being made in Afghanistan. 

The Pentagon stood by the timetable earlier this month. 

“There's simply no adjustment to the milestones," said Pentagon spokesman Army Col. Steve Warren. "But I think what's most important is that Gen. [John] Campbell has flexibility within those milestone to flow forces out at the pace that he sees most appropriate based on conditions on the ground."

Graham is also deeply skeptical of the Obama administration's negotiations with Iran over its nuclear program. 

"If we continue on the path we are with the Iranians, they'll wind up with a nuclear capability like North Korea and one day have a bomb," Graham said. "He's about to make the biggest mistake of his presidency."