Donald Trump’s firing of his campaign manager, Corey Lewandowski, sounds like a big deal, until you realize how little of a Trump campaign there is to manage.

Late Monday, hours after presumptive Republican presidential nominee Trump let his campaign manager go, new campaign filings revealed that Trump ended May with less than $1.3 million in the bank.

That might sound like a nice piece of change until you learn that Hillary Clinton, his presumptive Democratic opponent, raised more than $28 million in May and started June with $42 million in cash.

Even Trump’s fellow Republican Ben Carson reported $1.8 million — $500,000 more than Trump — in his campaign fund in May, even though he stopped campaigning in March.

Overall, Team Trump — his presidential campaign, the Republican National Committee and Trump’s allied super PAC Great America PAC — went into June with $21.7 million in cash. That compares to $103.4 million in cash on hand held by Team Clinton, which includes her campaign, the Democratic National Committee and the Priorities USA super PAC.

With that, the Clinton campaign spent $1.6 million in ad production and airtime, pummeling Trump with attack ads in battleground states. That compares to only $150,000 spent by Trump’s campaign on ads in May. He has preferred to attack “Crooked Hillary” in speeches, on Twitter and through other free-media-generating stunts.

Personnel? At last count, the Trump campaign had about 30 staffers nationwide, according to Associated Press, while Clinton’s team has more than 700 nationwide, including 50 people in the critical swing state of Ohio alone.

You could tell that Trump was in trouble when he stopped bragging about his polls, which have generated a drumbeat of bad news for his campaign since Clinton clinched enough delegates in early June to win her party’s nomination. On the morning after Lewandowski’s firing, Real Clear Politics’ daily average of major polls showed Clinton ahead of Trump by 45 percent to 39.2 percent.

That’s a big slide for Trump since mid-May, when polls showed the two in more of a dead heat and, in some cases, the New York developer slightly ahead.

But the polls give Hillary little reason to rest comfortably. She and Trump have the highest disapproval ratings — more than 50 percent for both — of any two presumptive major party nominees in the history of polling.

Indeed, the great irony of this campaign is the apparent anti-Clinton derangement syndrome that has driven Republicans to nominate Trump. Now the volatile, pouty-mouthed industrialist with insult-comic style and very little knowledge of government seems increasingly poised to snatch defeat out of the jaws of victory.

Yet Trump seems to be having too much of a good time in the spotlight to see the sinking of his own campaign ship. Buoyed up by billions of dollars in free media coverage generated by his hyperactive Twitter fingers, he seems to have overlooked the traditional pivot from campaigning to the Grand Old Party’s conservative base to appeal to moderate swing voters who will decide the November election.

Lewandowski recently defended his candidate’s no-frills approach. “We are leaner, meaner, more efficient, more effective. Get bigger crowds. Get better coverage,” Lewandowski said. “If this was the business world, people would be commending Mr. Trump for the way he’s run this campaign.”

Hah! Now Lewandowski is out and, if this were the business world, the Trump campaign would be teetering on bankruptcy.

Maybe Trump thinks he can rewrite the book on presidential campaigning by turning his celebrity into a campaign of stunts and free media.

Or maybe, as some suspect, he never intended to get this far with what started out as a brand-building stunt and happened to strike a long-neglected core of frustrated, displaced middle-class Americans.

Either way, he’s stuck with running now and appears to be headed either to a long-shot victory or a crushing defeat.

RNC leaders are divided between those debating how much they should help Trump and those who feel the party should dump him at next month’s national convention in Cleveland. That’s unlikely to happen. The party with the most disunity tends to lose.

Like it or not, loyal Republicans have little choice left but to support Trump’s campaign — if they can find it.

(E-mail Clarence Page at cpage@tribune.com.)

(c) 2016 CLARENCE PAGE DISTRIBUTED BY TRIBUNE CONTENT AGENCY, LLC.