US election polls tracker: who is leading in swing states, Trump or Biden?

Joe Biden is leading ​Donald Trump in the national polls for the presidential election. But that doesn’t guarantee ​the Democratic candidate victory. Hillary Clinton also had a clear lead over Trump in the polls for almost the entire 2016 campaign. She ended up losing in the electoral college. ​Because the presidential ​voting system assigns each state a number of electoral college votes, which​ go to the state’s victor regardless of the​ margin of victory (with the...