The next U.S. presidential election occurs in about 20 months, but the campaign season is already well underway. President Donald Trump is more than halfway through his first term. He has a solid political base of supporters and a firm grip on the Republican Party, and his nomination to seek a second term is unlikely to face a serious challenge. However, Trump’s blustery personality, stream-of-consciousness Twitter finger and controversial policies as well as the many, various dramas swirling around him make him an unpopular president, according to all the polls. This is attracting what may become a record number of Democratic hopefuls seeking their party’s nomination to run against him in November 2020. At last count, there are...