DENVER (AP) - Nomination within his grasp, Donald Trump would need to win over a broader group of voters in November beyond those who have helped clear the Republican presidential field for him.
As a whole, voters in the general election will be younger, more likely to be female and vastly more diverse than the predominantly white groups of the Republican primaries. In recent elections, those sets of voters have leaned sharply toward the Democrats.
To counter the Democrats' advantage among women, young people and black, Latino and Asian-American voters, Trump will have to maximize his support among whites - especially white men - to levels rarely seen.
His target, analysts say: winning about two-thirds of white voters, a feat reached in modern politics only by Ronald Reagan in his 1984 landslide.
"It's going to be difficult for him to increase his margins among some of the groups" that already support him, such as white men, said Karlyn Bowman, a demographer at the right-leaning American Enterprise Institute.
Ruy Texeira of the liberal Center for American Progress noted that Trump has performed well in the primaries among white college graduates, but polls indicate the businessman is disliked by that demographic in the broader electorate.
"People get so caught up in how well he's done in the Republican primaries, but that's just so very different from the kind of people who show up in November," Texeira said.
Some Republicans acknowledge the steep curve for Trump, who edged closer to clinching the nomination after winning Indiana on Tuesday.
"The guy is hated and detested by an extraordinary amount of the American electorate," said Whit Ayres, a GOP pollster who worked on Florida Sen. Marco Rubio's presidential campaign.
"It's not just one group that detests him," Ayres said, alluding to Trump's rhetoric on immigration and his incendiary comments about women. "He has been on a concerted effort to make enemies of millions of Americans."
Those trends could make it difficult for Trump to triumph in states such as Ohio and Florida, must-wins for Republicans to have any shot as retaking the White House.
Still, more Republican leaders are likely to unite behind him now that Texas Sen. Ted Cruz, Trump's nearest rival, has dropped out.
The likely Democratic nominee, Hillary Clinton, has her share of weaknesses, as well. Polls find voters don't trust her, and she's had to fight harder than expected against Vermont Sen. Bernie Sanders, who beat her in Indiana and has locked down the fast-growing youth vote.
"I'm not convinced at all that Hillary matches up well with Donald Trump in a general election," said Dave "Mudcat" Saunders, a self-described populist Democrat who ran former Virginia Sen. Jim Webb's abbreviated 2016 presidential bid. "If you're just fed up with all of it, why are you ever going to line up with her?"
Still, Trump has another barrier: his own party.
As partisan divisions have hardened, recent presidential nominees have counted on support from 90 percent or more of their political base. It's not clear Trump can rely on Republicans to that degree. He's only modestly increased his backing over the course of primary contests, even as rivals dropped out.
His ascendancy also has led to a movement among conservatives who have pledged never to vote for him, and many prominent Republicans plan to skip the party's summer convention in Cleveland.
Ohio Republican Chairman Matt Borges, who still backs his governor, John Kasich, for the nomination, insists Clinton's unpopularity will bridge any GOP gaps. "Ohio voters know the double-speak that has defined her career," he said.
Trump regularly boasts he can knock off Clinton. His supporters predict his appeal to working-class whites gives him a shot in recent Democratic strongholds like Pennsylvania or Michigan.
"I'll bring places in play that nobody else can bring," Trump told California's Republican Party convention. "For example, New York, I won it by landslide numbers."
The New York example, though, shows why Trump's performance in primaries doesn't necessarily translate to success in November. Clinton also won New York and received more than 500,000 more votes on primary night than Trump did. In the New York Republican primary that Trump won so convincingly, 91 percent of voters were white. Minorities comprise 42 percent of the state's population. Democrats outnumber Republicans in New York by a 2-1 margin and have carried the state in the past seven presidential elections.
Bowman said Trump's New York claim "seems completely ridiculous," though she and others allow that he could make inroads among Democrats, particularly if black voters are less enthusiastic about Clinton than they were for Barack Obama.
And, of course, there's plenty of time between now and the Nov. 8 election.
"There are a lot more shoes to drop before both conventions and throughout the fall," Republican pollster Greg Strimple said. "I don't think we can make anything of what's happening right now."