Can American elections be "nationalized"? What does that mean?

In this country, the states run elections. Congress is empowered to step in; the president is not. So what does it mean for the president to call on a political party to "take over." Is that allowed? What would that mean? And why is this happening now? We talk with Sarah Cooper from the Carter Center to understand who is in charge and whether anyone else can take charge. Learn more about your ad choices. Visit megaphone.fm/adchoices