For Steve Bannon, the way to create an enduring populist majority is to combine forces on the left and right. That's why he was in Italy earlier this year, where parties representing those two sides joined together in a governing alliance. That's why Bannon hopes to wean some of Bernie Sanders' supporters away from the Democratic Party. But the next place where we might be watching the rise of a new left-right populism is France.

Thus far, the "yellow vest" protests in France have lacked a party, structure and leadership. But lists of demands have been circulating. At their heart is an unworkable fantasy, such as a constitutional cap on taxes at 25 percent coupled with a massive increase in social spending. What is striking about these manifestos is that they combine traditional wish lists from the left and right. No wonder, then, that nearly 90 percent of people who back the major far-left and far-right parties support the movement, compared with only 23 percent of people in Macron's centrist party.

The "yellow vest" uprising has also spread to Belgium, where the fragile governing coalition has collapsed, largely over the issue of immigration. But there again, the protests have a feel of generalized discontent coming from left and right. Just as in France, America and Britain, it appears to be a rural backlash against urban elites.