Donald Trump may feel invincible right now, but he’s still an underdog going into the general election.

Hillary Clinton is the favorite to win in November at odds of 4-11, according to the online bookmaker Ladbrokes — meaning you’d have to wager $11 to win $4.

The New York City tycoon, meanwhile, is a 9-4 underdog, according to the bookmaker’s website.

Betting on the presidential race is illegal in the United States, but the online odds capture the zeitgeist.

“The interest is huge,” said UK-based Ladbrokes spokesman Alex Donohue. “We can’t get Donald Trump off the pages of our newspapers and our TV screens.”

So whom do the oddsmakers like for vice president?

Ohio Gov. John Kasich, who was the last man standing against Trump before he quit Wednesday, comes in at 4-1. Right behind him is New Jersey Gov. Chris Christie at 6-1, according to Ladbrokes.

Clinton hasn’t sewn up her party’s nomination yet, but the oddsmakers like HUD Secretary Julian Castro (9-4) for a running mate. Virginia Sen. Tim Kaine and Massachusetts Sen. Elizabeth Warren are tied at 6-1 in the Democratic veepstakes.

For Trump to overcome the odds, he’ll likely have to mend fences in the Republican Party. On Wednesday, he said he wanted to unify the GOP — and some Republican bigs have already kowtowed to the billionaire businessman.

“You know what, I think something different and something new is probably good for our party,” Republican National Committee chair Reince Priebus cooed on CNN Wednesday morning — after months of bashing Trump. “So, look, we’re here. We’re going to get behind the presumptive nominee.”

And Ed Rollins, President Ronald Reagan’s former campaign manager, climbed aboard the bandwagon earlier this week, saying he would head up a new pro-Trump super PAC.

Trump said on the “Today” show he was “confident I can unite much of” the party, but he still showed his trademark bite, saying there are some GOPers he finds so odious, he wouldn’t want their support.

“Those people can go away and maybe come back in eight years after we served two terms. Honestly, there are some people I really don’t want,” the presumptive GOP nominee said.

Apparently, the feeling is mutual because some Republicans have already said they would enthusiastically support Clinton over Trump.

“The GOP is going to nominate for president a guy who reads the National Enquirer and thinks it’s on-the-level,” Mark Salter, a top aide to GOP nominee John McCain in 2008, wrote on Twitter late Tuesday, adding, “I’m with her” — a Clinton slogan.

Steve Schmidt, the GOP strategist central to McCain’s 2008 campaign, told Politico that “a substantial amount of Republican officials who have worked in Republican administrations, especially on issues of defense and national security, will endorse Hillary Clinton in the campaign.”

Other GOP power players remain wary of Trump and have insisted they could never support him.

“The answer is simple: No,” tweeted Nebraska Sen. Ben Sasse.

A spokesman for George W. Bush says the former president does “not plan to participate in or comment on” the presidential race.

Team Clinton on Wednesday released a list of more than two dozen Republican and conservative pols, operatives and pundits who were already on record opposing Trump.

At any rate, voters should expect a bloody, six-month clash of the titans between Trump and Clinton — replete with vicious name-calling, a swamp’s worth of mudslinging and billions of dollars of ugly negative ads on radio and TV.

The fiercest fights are likely to be waged in populous swing states such as Florida, Pennsylvania, Ohio and Michigan, where the outcomes could determine the eventual winner.