Note: The above chart compares the amount spent by Donald Trump through September to the amounts spent by the other candidates through June. So even over the longer time period, Trump has spent far less than his opponents. With that out of the way...

MSNBC reported Tuesday morning that aides to Donald Trump estimate that the real estate mogul has spent roughly $2 million on his 2016 presidential campaign to date. That's consistent with a Wall Street Journal report from over the summer that Trump had loaned his campaign $1.8 million and raised another $100,000 for the effort.

That's stunning. And brilliant.

Trump has been the dominant force in the Republican presidential race for, at least, the past four months. (He officially became a candidate June 16.)  On any given Sunday, he is appearing on or phoning into some -- if not all -- of the Sunday talk shows. According to Facebook's new Signal interface, Trump is responsible for 80 percent (or more) of the conversation around the 2016 presidential race on any given day. The first two Republican debates netted 24 million and 23 million viewers, respectively -- totals that Trump, rightly, attributes to his presence in the race.

All of that attention has catapulted Trump to the top of virtually every national and early-state poll released in the last few months -- all without Trump ever having to dip into his pocket in any meaningful way. (For someone who is a billionaire, which Trump definitely is, $2 million is roughly the income hit of me buying a pumpkin spice latte.) Remember that Trump, as recently as August, pledged that he would spend as much as $1 billion of his own money on the campaign; "I make $400 million a year, so what difference does it make," he said in response to reporters' questions at the Iowa State Fair.

Trump is the living, breathing example of publicity that you just can't buy. And, to his credit, he's acknowledged as much. Trump told the New York Times last month that he had planned to spend $15 million on campaign ads over the summer but decided not to since he was getting wall-to-wall media coverage without spending a dime. "I’ve gotten so much free advertising, it’s like nothing I’d have expected,” he told the Times. “When you look at cable television, a lot of the programs are 100 percent Trump, so why would you need more Trump during the commercial breaks?”

He's right. Take Tuesday. He started his day doing an interview on CNN's morning show and will close it with a sitdown with Fox News's Bret Baier. The guy is a media-appearance machine.

The fact that Trump felt the need to spend only $2 million to date will reinforce the idea, rampant among the frustrated Republican establishment, that the media is Trump's best friend and is largely responsible for his rise. I've written before on why I think that misses the mark and robs Trump of some of the credit he deserves for assessing the political-media landscape and capitalizing on it. (Make sure to read the counter-argument on the media's role in Trump's rise by my colleague John Sides here.)

What's clear is that Trump is playing the game better than anyone else at this point. Is he gaming a political system that prefers simple answers to complex ones and a media world that puts ratings and clicks at the top of its priority list? Absolutely. But, that's the brilliance of Trump's campaign to date. He's recognized that as a celebrity with a massive following on Instagram and Twitter, he can dominate the political conversation without spending any real money in the process.

Will Trump be able to continue to float above the GOP crowd on free publicity alone? Maybe not. But did you think he would have made it this far by spending only $2 million? Me neither.