It’s an obvious irony of this election that the Democrats who were swept out of the Senate last night with reason to curse Barack Obama owed those very seats to him in the first place. They were the Democratic class of 2008, a motley bunch of newcomers from the country's reddest states, helped by an electorate built on the candidacy of the country's first African-African nominee. Six years later, it was Obama who weighed them down.
From the first stirrings of this campaign cycle, as Obama’s popularity faded quickly after 2012, the dynamics of his final election season as a politician were apparent. Republicans wanted to nationalize the race, make it about the president and public cynicism about the direction of the country. Democratic candidates responded by trying to localize their races. Mark Begich, Mark Pryor, and Mary Landrieu—who each had a father active in politics while Obama was in grade school—grasped at family legacies. Kay Hagan worked to reorient her race around state policy debates rather than national ones. Mark Udall searched for wedge issues that could split the Republican coalition.
None of those candidates succeeded in winning his or her argument. (Landrieu, who finished second tonight, has survived into a run-off, but her future in December looks bleak.) Democrats also lost a bigger bet that they could upend the central dynamic of modern American politics. Starting last year, party strategists made unprecedented investments to develop and scale tactics honed during Obama’s innovative campaigns. By maximizing the base vote, they reasoned, those idiosyncratic persuasion efforts could pull competent candidates over the finish line. It was, at its core, a bet less on the political environment than one on human behavior.
The reason the drafters of the Constitution granted six-year terms to senators was to ensure that only one-third of the chamber would be on the ballot in each federal election. This would insulate the Senate from the rapid change to which the House could find itself susceptible, ensuring that even in a sweeping national election like this one it couldn't swing from one party's filibuster-proof majority to another. With such long terms, elected senators had plenty of time—from fundraising to pork and constituent service—to indulge the opportunities of incumbency.
But changing demographics may mean twenty-first century senators are much less likely to grow old in their jobs than their twentieth-century predecessors. Over the last two decades, the two parties have cleaved dramatically along lines that mirror patterns of voter behavior. The drop-off in turnout from presidential to midterm cycles has suggested that voting every two years and voting every four years are distinct behaviors, and now they seem to be sorting out on partisan lines. With a base of older, whiter, married voters, Republicans have a coalition of those most likely to turn out every two years. Democrats may tout theirs as demographically "ascendant," but while minorities and young whites, particularly unmarried women, are growing as a share of the population, they are among the country's least reliable voters.
This shift can be seen most sharply in southern states, where older whites have abandoned the Democratic party with alacrity over the last two decades. (The New Deal generation has been, in actuarial terms, replaced by the Great Society generation.) Unlike governors, who nearly everywhere repeatedly face one of those electorates or the other, senators alternate. Those whose careers are launched by midterm voters face their first referendum with a presidential electorate, and vice versa.
Indeed, the Democrats’ still-unrealized dreams of turning Georgia blue were inspired by visions of a presidential electorate. Michelle Nunn is the most promising Senate candidate her party has produced in the state over nearly two decades. She nonetheless fared far worse than her party’s 2008 nominee, a bland lifelong politician named Jim Martin, who faced a stronger opponent than Nunn and managed—on the back of Obama-propelled turnout—to push him into a run-off.
Democrats are sanguine about their Senate prospects in 2016 because they'll face a crop of incumbents from Pennsylvania, Illinois, and Wisconsin, where the presidential electorate should be younger and more racially diverse than the one that sent them to Washington. What will Thom Tillis, Joni Ernst, and David Perdue to be able to do in the next six years to ensure that they can keep their seats when they face the 2020 electorate?