Governor Romney is suffering from political amnesia.

If we were to impose greater sanctions on economic sectors, I think we could have a significant impact on Putin.

I was the first Republican in the country to support the president's Clean Power Plan.

In the midst of our wars in Iraq and Afghanistan, Putin invaded the Republic of Georgia. Let's call it for what it is. Here is Vladimir Putin with a failing Soviet franchise. And when he can't win the hearts and minds of his neighboring nations, he uses energy extortion, masked gunmen and barbed wire.

There is scientific evidence that demonstrates there is some impact from human activities. However I don't think the evidence is conclusive.

You can see the actions that the Russians are trying to take in eastern Ukraine. And so it's so important that we take actions to deter further Russian aggression against the Ukrainian people.

[Putin] is a bully. And bullies only understand when we punch them in the nose, but we need to do that economically.