Jonah Goldberg‘s latest column at National Review Online contends that neither Hillary Clinton nor Bernie Sanders will be able to hold together the coalition of voters who elected — and re-elected — Barack Obama as president.

The trouble for Clinton and the Democrats generally is that while Barack Obama was able to unite the factions of the Left to get himself elected, it’s not clear anyone else can.

Obama wanted to be a Reagan of the Left, a “transformative” president who moved the magnetic poles of American politics leftward. The jury is out on that project, but he did succeed in at least one sense. Reagan united foreign-policy hawks, social conservatives, and economic conservatives — the famous three legs to the stool of the conservative movement.

Obama did something very similar on the left. He united the civil-rights or identity-politics wing, the economic or egalitarian wing, and the more elitist technocratic wing. Obviously, these movements overlap — just as the different factions of the Reagan coalition overlapped — but each has its own priorities and passions.

Aided by his experience as a former community organizer and his historic status as the first black president, Obama held the coalition together through force of personality.

The Democratic party has always had internal conflicts. Franklin D. Roosevelt’s coalition contained socialist Jews and blacks and Southern segregationists. That coalition held for 20 years after his presidency. But the Obama coalition seems to be fraying while he’s still in office. The black Left is angrier at the end of his presidency than it was at the beginning. The egalitarians think the country is worse off, and the technocrats are left trying to explain why their plans are so great, despite the fact that the economy has never really recovered on their watch. Moreover, none of Obama’s presumptive heirs have the charisma or skills to repair or sustain the coalition.