Sen. Rand Paul has called fellow Republican Sen. John McCain "a little bit unhinged" after McCain said "the senator from Kentucky is now working for Vladimir Putin."
The discord between two senators from the same party is remarkable even in the current political environment.
Paul's comments came in an interview on MSNBC's "Morning Joe." He was responding to remarks McCain made a day earlier while urging a Senate vote to include Montenegro as part of NATO.
Russia opposes Montenegro's inclusion in NATO. As debate ensued, McCain saw Paul come to the Senate floor and remarked that anyone who objected to his request would be carrying out "the desires and ambitions of Vladimir Putin."
Paul objected anyway.