McCaskill: If we don't 'take better care of the moderates' it's 'not going to be pretty'

"The problem now is the two ends are getting all the amplification. The political system loves the extremes, it doesn't so much show a lot of love for the moderates," McCaskill said.

But McCaskill argued her Republican colleagues have it worse than centrist Democrats, presumably because of the rise of the Tea Party movement.

"There seems to be more worry from our Republican colleagues that they have to hue to a pretty extreme agenda or they get taken out in a primary process," she said.

McCaskill, who serves on the Armed Services Committee, then segued to a discussion over recent violent protests in Afghanistan, calling for the United States to "recalibrate many parts of our mission" there.

"They're blowing up the highways we build, we're having to pay off the bad guys to get enough security … it's time for us to pulls hundreds of millions of dollars for highways and electrical grids out of Afghanistan and put it right into the infrastructure of the United States," McCaskill said.