Jay Cost of National Review Online explains why President Trump will need to expand his electoral coalition if he seeks another term in 2020.

Simply put, he is a “minority president” and cannot expect victory merely by winning the voters he carried in 2016. He needs to persuade Americans who voted for somebody else two years ago. He has not done this. …

… If you had told me in 2015 that the Republican nominee was going to lose Colorado, Nevada, and Virginia, I would have said that the Democrat was on track to win more than 300 electoral votes. But as we all know, that didn’t happen. Trump dominated the industrial Midwest and very nearly carried Minnesota — historically one of the most Democratic states in the post-war era.

Still, Trump won only 46 percent of the popular vote, less than Hillary Clinton, which makes him one of just a handful of presidents since the Civil War who won the electoral-college vote while winning fewer popular votes than their opponent. …

… Of course, defenders of President Trump will note that the presidency is not determined by a nationwide popular vote. Indeed, that is true. I am not contesting the legitimacy of the Trump election in 2016. Rather, I am pointing out that the anti-Trump vote was substantially larger than the pro-Trump vote — 54 percent to 46 percent. And even though the entirety of Clinton’s 3-million popular-vote victory came from California (which went for her by a margin of 4.3 million votes), Trump’s share of the vote in Michigan, Pennsylvania, and Wisconsin was less than what George W. Bush won in those states in 2004, when he lost all three states to John Kerry.

The implication is that Trump won because the anti-Trump vote was scattered across multiple candidates, mainly Hillary Clinton and Gary Johnson. The political danger for Trump in 2020 is that this vote, previously scattered, could come together around a single alternative to Trump.