Transcript for 28-year-old Democrat upsets powerful congressman

A stunning night in politics. Democrats shocked after one of their leaders beat by a social poised to become the youngest woman elected to congress as president trump scores more wins on the GOP side, our chief white house correspondent Jon Karl tracking all the results. Good morning. Reporter: This was a shocking defeat to the democratic establishment and a major victory to the Progressive, Bernie Sanders' wing of the democratic party. The political upset of the yore overnight. Looking at herself on television. How are you feeling? Can you put it into words? Nope. I cannot put this into words. Reporter: 28-year-old Alexandria ocasio-cortez, van kwoished one of the most powerful Democrats in congress, Joe Crowley. This is for Alexandria ocasio-cortez. Reporter: He had been believed to be the next speaker of the house. I respect the outcome of this election. Reporter: Ocasio-cortez calls herself a democratic socialist and proposed eliminating I.C.E., the immigration and customs enforcement agency. A former Bernie Sanders organizer, if she wins in know November she'll be the overwhelming favorite and become the youngest woman elected to congress. On Twitter, president trump saw Crowley's loss as his win. He's out. That is a big one that nobody saw happening. Perhaps he should have been nicer and more respectful to his president. And in South Carolina -- You got to get out there and vote. Reporter: -- A candidate endorsed by the president won. Governor Henry Mcmaster coming out on top in the Republican primary. Thank you. Reporter: Overnight the president extended his well wishes to a former opponent who won in Utah tweeting a congratulations to Mitt Romney on his senate primary win. Big and conclusive win by Mitt Romney. Congratulations. I look forward to working together. There is so much good to do. A great and loving family will be coming to D.C. With primary season almost over, the president is fully in campaign mode. He heads out on the campaign trail today for the second time this week. He'll be going to North Dakota and Wisconsin. He know, George, that his agenda is very much at stake. On the ballot in many ways. Let's bring in Matt dowd for more on this. Matt, in recent years we've seen Republican incumbents beat by the wings of their party. Haven't had upsets like this on the democratic side. A big, big development for the Democrats. George, I think this is a huge symptomatic leading indicator of what's going on in the party and in the country. This is like what happened with Eric Cantor, the majority candidate who lost. It signaled what was going to come in 2016. This is a district that was over 80% nonwhite and obviously Joe Crowley did not fit this district and the democratic party anymore and lost and this is going to tell us a lot about what's going to come ahead post-2018 but no doubt about it. This is an indicator light of what's coming for the establishment. If you're an incumbent in either party you have to be worried. I think if you're an incumbent you have to be worried and respond. The ones that have responded to what's changing in America have done reasonably well and won their parties so if you respond to it but the problem right now is Donald Trump was wrong about what happened in this district. It wasn't because Joe Crowley was anti-Trump. It was because Joe Crowley wasn't anti-Trump enough in the district and that's why he was beat in this primary. But it is a huge indication of the changing nature of both political parties. Big midterms coming up. Matthew dowd, thanks very much.

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