President Barack Obama’s sweeping victory in the 2012 election, his party’s wide win in the Senate, and the first ever triumph of marriage equality at the polls cemented the reality of a changed America that emerged in 2008.

The shape of that changed country was obscured by the Republican revival of 2010, but the 2012 vote means both the survival of Obama’s policy project and the clear emergence of a new demographic picture and electoral map.

The first post–baby boomer president was returned to the White House with the widest, clearest reelection win since Ronald Reagan won 49 states in 1984, yet a smaller mandate than his own 2008 victory. And Democrats now have, in Obama, their Reagan: A figure both historic and ideological, who can carry, if not quite fulfill, a liberal vision of activist government and soft but sometimes deadly power abroad that will define his party for a generation.

Obama lacks Reagan’s sweeping victory, and presides over a more deeply divided country than when he took office. But the breadth of his accomplishments have been validated by Tuesday’s vote. ObamaCare is now a firmly rooted component of the nation’s social compact. Americans appear to have accepted his campaign’s argument that he deserves more credit for a nascent economic recovery than blame for its slow pace.

And the vision of a conservative resurgence appears to have fallen short. The best the Republican Party could muster was a Massachusetts moderate masquerading as “severely conservative.” The Tea Party is a memory, an embarrassment to a party that didn’t even mention it at its national convention in Tampa. And the network that led the conservative resurgence, Fox suffered a sort of televised meltdown as the results came in, with Karl Rove berating host Megyn Kelly for calling the election, he said, prematurely.

Republicans have warned of a more liberal Obama over the coming term, an outcome Democrats hope for and consider likely. But the scale of the decisions facing the country will create an intense pressure for compromise, and now on Democratic terms.

But the 2012 election marked a cultural shift as much as a political one. Ballot measures that had failed for years — allowing the marriage of two men or two women in Maine and Maryland; legalizing marijuana in Washington state and Colorado — were voted into law. The nation’s leading champion of bank regulation, Elizabeth Warren, handily defeated moderate Sen. Scott Brown in Massachusetts, and the nation’s first lesbian senator, Tammy Baldwin, was elected in Wisconsin. Even climate change, which was absent for nearly the entire campaign, came roaring back with Hurricane Sandy and was the subject of endorsements for Obama and harsh attacks on Romney.

These measures were passed, and Obama reelected, by an American electorate that Republicans had dismissed as a fluke of African-American pride and youth enthusiasm, and which a generation of pundits — Michael Barone, George Will — wrote off as a fantasy.

The Romney campaign, in fact, bet its last weeks on modeling showing a more Republican, older, and more white electorate — the reversal of the younger, diverse crowds which propelled Barack Obama to the White House four years ago. But in fact the share of 18- to 29-year-old voters increased by a percentage point, while the number of white voters declined by two. Their votes were more balanced this time, but the change has been unmistakable and irreversible.

The groups on whom Obama depended are the ones that are growing; white men, the core Republican constituency, are a shrinking minority. For the first time In 2011, minority births surpassed white births in the United States, and the longer demographic trend places white Americans in the minority by 2041.

The Republican Party will spend much needed time in the wilderness after this election, even as the open race for 2016 unofficially kicks off today. The future of the Grand Old Party will be determined by how well it adapts to the brand-new Liberal America — indeed the Obama America — that is now here to stay.