Hillary Clinton should be careful what she wishes for. Donald Trump's profound weakness as a general election candidate might make Clinton president — but a landslide victory might also destroy her presidency.
Since a big win usually translates into a large mandate, this might sound counterintuitive. Just look at Reagan's 49-state landslide in 1984. But sometimes a landslide can lead directly into a crisis of legitimacy.
In 1964, Barry Goldwater received almost no support from the establishment and lost all but six states. But after his blowout victory, President Lyndon Johnson quickly ran into two coalition-shattering features of the 1960s: the civil rights movement and the Vietnam War. It did not help Johnson that it seemed like he never earned the presidency, having initially assumed office after John F. Kennedy's assassination and then beating an unusually non-competitive Republican nominee. In 1968, Johnson announced he would not run for re-election, and the new wings of the Democratic Party engaged in a bitter primary feud.
Clinton doesn't compare easily with Reagan or Johnson, but the election feels more like 1964. She may blow out Trump in a general election. But that will hardly disguise her fundamental unpopularity at large. "No major party nominee before Clinton or Trump had a double-digit net negative 'strong favorability' rating. Clinton's would be the lowest ever, except for Trump," wrote Harry Enten at FiveThiryEight, in May.
When George W. Bush won a relative "squeaker" election in 2004, he claimed to have a definitive mandate. But Clinton could win by a much larger percentage this year, and she will be saddled with an electoral coalition that is much larger than the group of people who could honestly be described as her fans. This coalition will be filled with people who merely opposed Trump due to his unstable character, and it would be far too large and too incoherent to be satisfied. It will have contradictory goals and needs. And both ends of her coalition will argue that the size of her victory gives her the freedom to ignore the other side's priorities.
Consider foreign policy. Clinton inherits a party from Barack Obama, who skewered the "Washington playbook" on foreign policy. She is the de facto candidate of liberals and mainstream progressives, and therefore she represents a coalition that is skeptical of American military power when deployed in wars of choice. But Clinton has also won over almost the entire foreign policy establishment, including many of the names most prominently associated with promoting a war with Iraq in the late 1990s and early 2000s. Clinton may even be courting Henry Kissinger, the chief foreign policy hand of the Nixon administration who many on the left wing of the Democratic Party would have liked to see imprisoned for war crimes.
A crisis with Iran, or in any number of the Middle Eastern conflicts where American troops are involved, would throw her coalition into open warfare. Much of her base wants a foreign policy more dovish than Obama's, and they support her because they believe she is less hawkish than the touchy, volatile Trump. But much of her elite support will come from dogged interventionists, who support her because Trump draws inspiration from isolationists and America Firsters. The foreign policy elite trust that Clinton will stand up to America's rivals, whereas Trump will dismantle the American-led global order.
The left will argue that the interventionists can slink back to the Republican Party and challenge her in 2020. And the centrist hawks will argue that the left has nowhere else to go, and that durable majorities need the establishment and the lion's share of moderates. Similarly fractious splits are imaginable on trade, energy policy, or even social issues.
Clinton can't help that she faces a disorganized cretin as her Republican opponent. And given the alternatives, she'll surely take this problem over any other that could be offered to her now. But if she continues to lead Donald Trump by 8 or 10 points in the polls, her coalition will begin to expect the world from her. The normal discipline that is imposed by a competitive race will disappear almost entirely.
The disruption of American politics is only just beginning.