The brutal numbers behind a very bad month for Donald Trump

Supporters of Donald Trump got an unexpected plea on Saturday: a request to send the billionaire money.

It was an "emergency" request, the Hill reported, representing an urgent need for an infusion of $100,000 to put ads on the air in battleground states. Why Trump couldn't simply write a check to cover the costs apparently wasn't explained, but the missive was useful regardless: It demonstrates clearly the difficult position of the Trump campaign with only 142 days to go.

"(T)here's no way to look at Trump's national polling that avoids the grim reality that he is at a lower ebb than any general election candidate has hit in the last three elections," the National Review's Dan McLaughlin wrote last week.

Not only are Trump's poll numbers slipping, they are at a low that no one, Republican or Democrat, has seen in the past three election cycles. Looking at the window of time between 200 and 100 days before each of those elections, you can see that Trump has consistently polled worse than George W. Bush in 2004, John McCain in 2008 and Mitt Romney in 2012. He caught up briefly after clinching the GOP nomination – and then sank again.

[Clinton's lead over Trump slips after Florida shooting: Reuters/Ipsos poll]

The margin by which he trails Hillary Clinton now mirrors McCain's deficit to Barack Obama in 2008. McCain rebounded after the Republican convention – but it's important to remember that we're comparing Trump to the worst Republican performance in a general election since 1996.

There's every reason to think that those numbers will get worse. Trump essentially has no campaign at this point; there's no sign that he has started staffing up significantly. His campaign was never a traditional, national effort.

He has indicated that he doesn't plan to increase staff, either. On Friday, the Associated Press reported that Trump intended, in effect, to outsource his campaign to the Republican Party. As of right now, "the campaign estimates it currently has about 30 paid staff on the ground across the country," according to the report.

On Sunday morning, NBC News's Mark Murray shared numbers on ad spending by Trump and Clinton. In June 2012, the Romney campaign and PACs supporting it spent about $38 million on ads in battleground states – a bit behind the $44.6 million spent by Obama and his allies.

This June? Trump is getting skunked by Clinton, who is spending millions in swing states such as Ohio, Florida, Nevada, Colorado, Virginia and North Carolina.

In their look at the 2012 election, our John Sides and UCLA's Lynn Vavreck found that ads made a difference in the race when the balance was lopsided, as it is now. They also found that the presence of staff on the ground made a slight difference in the margin for a candidate in that region. (Without his field operation, they estimate, Obama probably would have lost Florida.) It's very early; Sides and Vavreck also found that ads right before the election made the biggest difference.

The current gap in ad spending exists because Trump can't or won't spend money on ads, just as he can't or won't spend money on staff. He will probably trail Clinton in fundraising even if he were to focus on it, and he has said in the past that he didn't need to spend because he got so much free media.

In essence, Trump is running a real-time experiment in a new form of presidential campaigning. And the early numbers suggest that the experiment is shaping up to be a failure.