The Democratic Congressional Campaign Committee has come under fire for interfering in a handful of Democratic primary races around the country. In trying to clear the primary field for the more moderate candidate they think will be the strongest in the general election, party leaders have drawn the anger of some progressive Democrats who think that the mere attempt to do so is corrupt and undemocratic.

I beg to differ.

No other political parties in democracies in the world have abdicated their leadership role as much as America’s have, weakening themselves and their ability to govern in the process. Party leaders have essentially given away the most important power they have — to determine who can run and win under the party’s banner. This power now rests exclusively with primary voters.

This is not to say that there is no role for primaries. But the pendulum between the party’s leaders choosing its candidates and primary voters choosing them has swung so far in the direction of the voters that even the smallest, most modest efforts to intervene in nomination races are deemed illegitimate.

The debate over party meddling erupted anew this week when the House Democratic whip, Steny Hoyer, was secretly taped by Levi Tillemann, a candidate in Colorado’s Sixth Congressional District primary. When Mr. Tillemann asked if he should step aside for Jason Crow, an Army veteran who many people think is the stronger candidate, Mr. Hoyer agreed.