.NO PRESIDENTIAL argument has actually had as much impact on a vote-casting as that between Joe Biden as well as Donald Trump on June 27th. Mr Biden's performance was therefore dreadful that his own party pushed him to leave. Because Kamala Harris, the vice-president, replaced him as the Democrats' candidate the race has tightened. It is actually currently a toss-up, according to The Economist's design. On September 10th Microsoft Harris will certainly face Mr Trump in a 2nd presidential discussion. How much difference will this set create?