New York Times contributing columnist Tom Edsall is a national resource. In column after column, he provides encyclopedic research both scholarly and journalistic, extended interviews, astute insights, and hard questions for progressives on politically urgent topics.

His most recent column, on the political consequences of the decline of unions, is no exception. As Edsall demonstrates, the Republican right’s strategic war on unions has been devastating to Democrats, since union members and union families, with their sense of solidarity and better understanding of how capitalism works, are more likely to vote for Democrats than demographically similar non-union families.

Edsall was not exaggerating when he wrote that the right has a better appreciation of unions than the left. Thus, the systematic union-bashing. In Wisconsin, as Edsall shows, courtesy of Scott Walker’s anti-union crusade, the union share of Wisconsin employees was cut from just over 15 percent as recently as 2008 to just 8.1 percent by 2018.

Edsall ends his piece by wondering why “many liberals and Democrats” don’t get the importance of unions.

The problem in building support for a resurgent labor movement is that many liberals and Democrats do not appear to recognize the crucial role that unions continue to play not only in diminishing the effects of inequality, but in voter mobilization and campaign finance.

And here is where Edsall misses a key part of the story. The problem is not that “Democrats” fail to appreciate unions. It’s that the corporate and Wall Street Democrats who have dominated the presidential wing of the party since Jimmy Carter and Bill Clinton actively loathe unions.

Carter, Clinton, and Barack Obama all had the opportunity and the votes to put serious teeth back in the Wagner Act, in the face of vicious corporate union-busting. All three decided not to lift a finger on behalf of labor law reform.

All three presidents had progressive labor secretaries. But the real power players were elsewhere.

Most Democrats in Congress get unions. The problem has been the corporate influence on the presidential arm party, and corporate domination of key positions at Treasury, OMB, and Legislative Affairs. Some of this is about campaign finance, but not all of it.

Edsall brilliantly depicts the class warfare that leads Republicans and their business allies to bash unions. He misses the fact that the same class warfare has infected the Democratic Party.