SEN. AMY KLOBUCHAR, D-Minn.:

Well, I believe this is much more than the resignation of one national security adviser.

You already had the Trump campaign chairman step aside because of contacts with Russia, and now this new report that there were multiple contacts between people in the campaign and Russian intelligence people. So, that's why I think we have to get to the bottom of it.

This is about a fundamental concept, and that is a free democracy that should be free from foreign influences. And we already have had our 17 intelligence agencies tell us that there's been an attempt to influence our election. And now we're finding out that these contacts were ongoing.

So, we need to know, who did Flynn work with? Who did he talk to? What did he talk about to the Russian ambassador? And, also, why was this happening? I think that's the biggest overriding question for our national security. Why was the Trump administration so eager to placate the Russians and make friends with them, when they have done so many horrific things, including invading countries that are our allies?