There is a country in the European Union saddled with a massive debt pile, rising borrowing costs and governments that collapse in a matter of months—and it’s not Italy. France, rather, is sliding into a morass that once plagued its southern neighbor. If French Prime Minister François Bayrou loses a Sept. 8 confidence vote on his efforts to rein in the country’s budget deficit with 44 billion euros—roughly $51 billion—in cuts, he will become the fourth head of government to lose his job in a year and a half. High turnover in the prime minister’s office was once rare in...