Krugman is not a Leftist in any sense, he is a centrist Dem by historical standards who hasn't changed his basic political orientation as the country has swung right. Much as how former Justice Stevens became a 'liberal' after being appointed by Ford and the sitting through three decades of reaction. But back to Krugman, remember he supported NAFTA when the House almost rejected it.
Keynes also was a conservative by the standards of his time, or at least in relation to the powerful Communist, Anarchist and Socialist currents that then existed. He essentially was trying to save the system from itself.
1'What’s Left of the Left' - New York