Trump surprised viewers with the unexpected response - one that became the top tweeted moment of the night.

Republican Donald Trump and Democrat Hillary Clinton face off in the second presidential debate Sunday night at Washington University in St. Louis, Missouri. NPR's politics team is live annotating the debate.

On this occasion, the often dour Clinton gave way to beaming smiles and occasional chuckles. Trump had just one salient objective - to project a calm and presidential air - yet struggled with it.

As Hillary Clinton and Donald Trump square off in the first presidential debate showdown NPR will fact check the candidates' statements live.

The presidential candidates traded barbs over their economic and trade plans, national security and race relations in the U.S.