Republican leaders awoke Wednesday to witness their grim future.

Without a makeover, a party that skews toward older, white and male voters faces political peril in an increasingly diverse and complex America.

President Obama’s decisive victory over Mitt Romney served as a clinic in 21st-century politics, reflecting expanded power for black and Hispanic voters, dominance among women, a larger share of young voters and even a rise in support among Asians.

Nationally, the steady and inexorable decline of the white share of the electorate continued, dropping to 72 percent, down from 74 percent in 2008 and 77 percent in 2004.

The Hispanic share grew again, encompassing one in 10 voters nationally and reaching higher levels in states such as Colorado, Nevada and New Mexico, which have become comfortable turf for Democrats in presidential politics.

In Colorado, a state many Republicans thought they could win, Obama won three-quarters of Hispanics, up from 61 percent in 2008.

Obama increased his Hispanic performance along similar lines in Florida as well, a result that included Democratic dominance in the heavily Puerto Rican swing precincts around Orlando and the election of a Cuban American Democrat to Congress, symbolizing the end of the GOP’s decades-long lock on that community.

In Ohio, African Americans showed up in large numbers and offered near-unanimous support to reelect the country’s first black president, making up 15 percent of the electorate in a state long known for the political power of its white working-class voters.

The Republicans’ troubles were further illustrated in a string of victories for gays, including voter approval of same-sex marriage in Maryland and Maine and the election of the country’s first openly lesbian U.S. senator in Wisconsin, a state many Republicans thought would swing their way.

Obama’s triumph showed how Democrats win in the modern era, using targeted messages to piece together ethnic groups while adding enough white voters in the old Rust Belt.

The challenge for them moving forward will be re-creating that patchwork in a post-Obama era, when candidates may lack the charisma or connection to the party’s core African American constituency. And a Republican candidate could emerge as an Obama-type figure for the right, turning politics upside down again.

Still, that Tuesday’s results assured victory for an incumbent presiding over a still-fragile economy, high unemployment and a record of enacting widely divisive legislation, such as his health-care overhaul, confounded many Republicans, who had hoped that Obama’s 2008 strength reflected an anomaly and not a trend.

“We’re going the way of the dinosaurs, and quick,” said David Johnson, a top GOP strategist in Florida. “The meteor’s already hit, and we’re just trying to wonder what the blast zone will look like.”