The American left risks making the same mistake as the far right in blaming its political failures on the alleged impurity of its leaders.

The defeat of establishment-backed Democrats in New York and Massachusetts at the hands of Alexandria Ocasio-Cortez and Ayanna Pressley, respectively, is giving the left hope that America is finally ready for social democracy.

They wants Democrats to campaign on debt-free college education, Medicare-for-all, abolishing Immigration and Customs Enforcement (ICE) and impeaching President Donald Trump.

They are appalled that Nancy Pelosi has promised to restore pay-as-you-go budgeting in a Democratic Congress — requiring spending cuts or tax increases to pay for new policies — fearing this will make overhauls of education, environmental law and health care impossible.

There are several problems with this attitude.

Problems

• Debates over Barack Obama-style incrementalism versus Bernie Sanders-style purism are more intense among those who tweet and write about politics than among voters, as David Leonhardt has argued in The New York Times. Most Democratic candidates, left-wing or centrist, are running on pocketbook issues.
• In competitive districts and states, Democrats are nominating and electing candidates who appeal to the middle: Doug Jones in Alabama, Conor Lamb in Pennsylvania, Ralph Northam in Virginia.
• Establishment figures, such as Senators Dianne Feinstein, Joe Manchin and Bob Menendez, have seen off left-wing primary challenges.

But most importantly:

• Democratic leaders look at the electorate and see that middle-class voters, mostly white, especially in the suburbs, and especially women, are leaving the Republican Party. Those are the sort of voters the Democrats need to tip the balance in states like Florida, North Carolina, Pennsylvania and potentially Arizona and Georgia. Party leaders believe those voters are more likely to be persuaded by fiscally responsible, center-left policies than a “democratic socialist” agenda.

Motives

Maybe party leaders are wrong. Maybe now really is the time for a leftward turn. Maybe fewer Republicans are persuadable than they think. By all means, have that debate.

But don’t impugn their motives. That leads down a dangerous path.

On the right, opportunists for years alleged that party leaders were betraying the “grassroots”. Rather than explain to voters that give-and-take is a normal part of politics and that you can’t get everything you want with control of only half the government, these opinionmakers promoted a false stab-in-the-back narrative, which led to a constant purification of Congress. Now the party is beholden to Freedom Caucus fanatics, Fox News talking heads and Donald Trump.

Democrats, don’t make the same mistake.