Yes, it’s clear that other Democratic candidates can’t replicate Obama’s coalition, at least when he’s not running; both common sense and the Chambliss run-off told us that a year ago. Yes, it’s also clear the war in Iraq, the financial crisis, and Katrina have not discredited all Republicans for all time. But we have not yet ruled out the possibility that Obama will realign American politics and serve as the liberals’ anti-Reagan. Reagan’s popularity went pretty low in his first term; his party had a disastrous House election in 1982, and a disastrous Senate election in 1986. We now see those elections mostly as blips on a Republican trendline. Conservatives should work to keep Tuesday’s elections — and next year’s elections, for that matter — from being remembered similarly.