The New York Times reports that West Virginia Gov. Jim Justice, a Democrat, will switch parties tonight in an appearance with Donald Trump:

Speaking to reporters in the White House Thursday, Mr. Trump promised “a very big announcement” at a gathering in Huntington, W.V., that is expected to draw thousands of supporters from across Appalachia, a region that gave Mr. Trump some of the largest margins of his election.

This is the opposite of a shock. Justice was once a registered Republican. He openly campaigned on his friendship with Trump and the two share a disdain for business ethics: He is the state’s only billionaire, a coal baron whose companies owed $4.4 million in unpaid taxes earlier this year. His defection is also conveniently timed. Justice is fresh from a bitter budget fight—one that he mostly lost. His announcement can be viewed as an attempt to curry favor with a state that overwhelmingly voted for Trump.

But there are deeper currents to note. Justice’s defection is made possible at least in part by the Democratic Party itself. Its infrastructure in conservative areas is notoriously weak. There’s not much evidence the state party even wanted an alternative to Justice, which is itself proof of a troubling tendency: The party backs conservative candidates in states like West Virginia because its leadership believes that is the only way to win elections there. This is a strategy that sacrifices long-term progress in favor of short-term electoral gains, and prevents the party from building up a progressive presence. Further, it leaves the party particularly vulnerable to defections.

If Justice indeed switches parties tonight, Democrats should rethink this strategy. Voters have no reason to vote for Democrats instead of Republicans if there’s literally no difference between Democratic and Republican candidates. Justice may inadvertently do the left a favor.