This is true, and it lies at the heart of one of the central ironies of the election. A Trump/Clinton match-up was supposed to be a head-on collision between the “old majority” and the “new majority.” Trump was going to pile up older white voters like no Republican nominee in recent history and Hillary was going to pile up minorities and young adults — both pillars of Obama’s two easy victories — and whoever had the biggest pile on Election Day would win. In reality, Trump’s weakness with key subgroups among whites is killing him. He’s winning big with less educated white voters, as everyone expected him to do, but white college grads are tilting Democratic this year and white women aren’t nearly as enthusiastic about him as white men are. He’s doing well enough with minorities (by which I mean he’s doing terribly but not far off Romney’s pace in most polls) that he really might be in command of the election right now if he was as strong with the “old majority” of whites as he was cracked up to be. He isn’t. Not yet.

But by the same token, Clinton isn’t nearly as strong with the “new majority” of minorities and liberal young adults as Obama was — not yet, anyway. New data out of Florida:

The poll by Miami-based Bendixen & Amandi International and The Tarrance Group shows Clinton drawing 53 percent among Florida Hispanics, compared to Trump’s 29 percent. That’s a significant 24-point lead. But Obama hit 60 percent among Latinos in 2012, according to exit polls. He defeated Mitt Romney in Florida by a single percentage point.

“She should not only be where Obama is — she should be beating those numbers, and she’s not,” pollster Fernand Amandi told the Miami Herald. He conducted the survey for Univision and The Washington Post from Aug. 24-Sept. 3. Hispanics make up 15.4 percent of Florida voters…

Among Hispanics, Clinton is also underperforming compared to Obama in three other heavily Hispanic swing states polled: Arizona, Colorado and Nevada. But she holds even wider leads over Trump in those states. Compare her 24 percent margin in Florida with 50 percent in Arizona, 45 percent in Colorado and 46 percent in Nevada.

Trump is also underperforming Romney’s share of Latinos in Florida in this poll, but in other polls across the country he frequently cracks 20 percent of the Hispanic vote. Romney pulled 27 percent nationally in 2012. For all of the sound and fury over Trump’s immigration policies this year, he might end up doing no worse than Mitt did. And Hillary Clinton, I thought, might be stronger with Latinos than Obama was even without the help she’s getting from Trump in appealing to them. She often clobbered Obama among that group in the Democratic primaries in 2008. But, for the moment, she’s not even keeping pace with O’s general-election numbers among Latinos. She’s just too flawed of a candidate, it seems, to get that group of voters really excited about her, even with Trump as a foil.

The Obama fan club that’s hurting her the most, though, is young voters. Harry Enten broke that down a few days ago:

Without good data, you might assume that Hillary Clinton is doing just as well with this group. She is essentially running for a third Obama term, after all. But new SurveyMonkey data (shared with FiveThirtyEight) suggests that Clinton is winning under-25 voters by half as much as Obama did. And, moreover, the data suggests that these voters should be solidly Democratic…

Are younger millennials simply more Republican-leaning? It doesn’t seem so. In fact, under-25 voters are more likely than any other age group to approve of the job Obama is doing as president…

Under-25 voters aren’t backing Trump in unusually large numbers. Instead, they’re either backing a third-party candidate or saying they’re undecided. (Bernie Sanders did especially well with those under-25 voters in the Democratic primary.) Indeed, when SurveyMonkey asks 18- to 24-year-old voters to choose between Clinton and Trump (i.e., no Johnson or Stein), Clinton’s lead expands from 13 percentage points to 23. That’s the biggest jump for Clinton among age groups between the four-way and two-way race.

More than once in polls this year Gary Johnson has actually passed Trump for second place among young voters once the pollster offered people a third-party option instead of the familiar binary choice. Young adults really don’t like Trump, it seems, but they’re sufficiently ambivalent about Clinton to be holding on out her right now in great numbers. The good news for Trump is that there’s no sign yet of any dam-break in Johnson’s support nationally, which means he’s still hoarding those young adults from Clinton. The bad news is that that might change in November if the election looks close. If Johnson’s young voters head for the lifeboats, they’re probably going to paddle towards Clinton. Consider all of this further evidence of why Obama is on the stump today and will be back on the stump repeatedly over the next two months. If Hillary can’t convince young voters to re-create the Obama coalition for her, maybe he can.