Is U.S. at a "dangerous" polarization point in foreign policy?

The ongoing negotiations with Iran over its nuclear program continue to rile Washington. Democrats called a letter from Senate Republicans to Iranian leaders "unprecedented and reckless." The letter warned Iran that any deal brokered with President Obama could be undone by his successor.

Former White House senior adviser Dan Pfeiffer, who just left his job at the White House Friday, told "CBS This Morning" co-host Charlie Rose that the country is "at a very dangerous point in our polarization of foreign policy."

Pfeiffer thinks the letter is an attempt to undercut President Obama's authority.

"First we've got to see if we can get a deal, and they are working on that. And the second is we're going to have to sell it. And think the challenge, which he has done and will do again, is to say to the Republicans, 'What is your alternative? If you don't get to a diplomatic solution, are you suggesting that we use force? Are you suggesting we go to war with Iran?' And then you're going to have to go to the American people and explain the consequences of that," Pfeiffer said.

Earlier this week, Iran's foreign minister Mohammed Javad Zarif brushed the letter aside, saying it "has no legal value and is mostly a propaganda ploy."

Watch Pfeiffer's full conversation on PBS' "Charlie Rose" show Wednesday night. To look up what time the show airs in your city, visit PBS.org.