In the late sixties, the left in the Anglo world still had political power, which was exercised through left-associated political parties, i.e., the US Democratic Party, Britain’s Labour Party, Canada’s New Democratic Party and Australia's Labour Party. Such influence depended in large part on the financial support and intellectual resources that that labor unions provided left-wing parties.
But globalization killed the trades union movement as a significant political force, as imported products of sweatshop labor destroyed the competitiveness of unionized industries. Freed of control by organized labour, traditional left-wing parties became parties of opportunism, led by the likes of Tony Blair (“Labour must seize the middle ground”, i.e., become an alternative to the Conservative Party by adopting their policies) and the Clintons. The result was ever more rapid globalization, culminating in the 1994 Gatt Agreement signed into American law by Bill Clinton, which placed American workers in direct competition with sweatshop labor in China and other Third-World countries where workers earned less than 5% of American wages.
So the leadership of the left that Paul Craig Roberts summons to put right the wrongs that globalization has inflicted on America's working people long ago joined the fascist leadership. Thus Roberts is deluded in assuming that there is a left movement out there that can somehow remedy the disastrous policies of the current supposed left leadership. Most of the left leadership of old, the Clintons, the Blairs, the former EU President, Barroso, have accepted their bank directorships, consultancies, and PR jobs as the reward for joining the globalists, imperialists and warmongers. As for the mass of working people, they are as helpless in the face of the ruling powers as revolting peasants ever were, except now, instead of peasants with pitchforks versus the cold steel of mounted soldiers, it is a few crazed advocates of the Second Amendment versus Homeland Security with its concentration camps, its armored cars and its stash of six hollow point bullets for every American citizen.
The power of the masses in America will never be restored other than as the result of an elite revolt, which is what the Trump movement seems to represent. But if Trump gains power, his long-term influence will likely be slight unless he restores to the working classes the means to create a powerful labor-based political structure with the clout that used to be wielded by the Teamsters, the UAW and the other great unions at the peak of their power.