Joe Biden’s chances do not look good. The Democrats have no plan B

SITTING PRESIDENTS do not tend to abandon bids for re-election. The most recent to do so was Lyndon Johnson, in 1968. And that is a year that his party, the Democrats, would rather forget. Johnson was unpopular. The country and the party were divided by the Vietnam war and the civil-rights movement. After a surprisingly strong challenge in the first primary, he stood aside, only to unleash chaos. One of the leading candidates to replace him, Robert Kennedy, was assassinated. The nomination was eventually awarded by party grandees to a man who had not won a single primary, Hubert Humphrey. In the end the Republican candidate, Richard Nixon, who had been widely considered unelectable at the beginning of the year, won convincingly. He went on to do more damage to the presidency than anyone bar the Republicans’ likely candidate this year, Donald Trump.