“Second presidential terms are almost without exception very difficult for the president and his team, for the government and the country,” writes Harvard economist and former Treasury Secretary Larry Summers. Well, yes. But some second terms are less unsuccessful than others.

Summers is persuasive in arguing that most presidents in the last three-quarters of a century have made their major marks in their first terms. But second terms are not always disastrous. Ronald Reagan pushed through bipartisan tax reform, an arms control agreement with the Soviets and a weakening of the Soviet empire that resulted in its collapse shortly after he left office. And his vice president, George H.W. Bush, was elected to succeed him by a 7 percent margin, one not exceeded by any presidential candidate since. Bill Clinton — and it was in his second term that Summers served as Treasury secretary — negotiated Medicare and fiscal policies that resulted in a balanced federal budget. His vice president, Al Gore, received a plurality of popular votes in the next election, although not enough electoral votes to win.