During the course of his campaign, Donald Trump's estimates of how much it will cost him to run for president have varied. He kicked everything off last June by bragging about his $10 billion net worth (per himself) and how he didn't need to raise money because he could pay his own way. He might spend a billion of his own money to run, he said, though he'd need to sell some buildings.

Once he got the nomination, though, he figured he might as well let other people chip in to pay the costs. He enrolled a fundraiser and is ramping up events to bring in contributions.

What's the bar he needs to hit? In 2012, both President Obama and Mitt Romney had more than $1 billion spent on their campaigns, according to the Center for Responsive Politics. A big chunk of the money spent on behalf of Romney was from outside groups; Romney and the party spent about $836 million combined. (The candidate can help raise for all three buckets, with different limits.)

That's for a full-bore, lots of ads, lots of outreach campaign. Which, apparently, is not what Trump says he wants to run.

In an interview with Bloomberg, Trump downplayed his fundraising goal.

"There’s no reason to raise" $1 billion, he told Michael Bender and Jennifer Jacobs. "I just don’t think I need nearly as much money as other people need because I get so much publicity. I get so many invitations to be on television. I get so many interviews, if I want them."

This isn't a new argument for Trump, either. He's repeatedly trumpeted how little he spent over the course of the primary season, in part for the reason he articulates there. If he can get free news coverage any time he wants, why buy ads? If media outlets conduct polls and report on them, why should he pay for his own?

But as with so many things in Trump's world, his comments to Bloomberg at this point may have also been a way to try to inoculate against bad news.

How Donald Trump and Hillary Clinton are seeking six-figure checks from individual donors for their respective White House bids and down-ballot candidates (Sarah Parnass/The Washington Post)

On Tuesday night, as Trump was officially locking up the Republican nomination, the Wall Street Journal reported that he was already behind the ball when it came to fundraising. While Hillary Clinton is just gearing up for general election fundraising, she has a long-standing fundraising team in place, and a big set of donors and fundraisers to hit up for contributions. Trump doesn't.

The dagger in that article was this paragraph, quoting well-known Republican fundraiser Fred Malek:

[Malek] called Mr. Trump’s fundraising disadvantage “huge and not widely understood.” He added: “Unless he’s willing to write a huge personal check, which is unlikely, I believe Trump will have a financial disparity of $300 million to $500 million.”

Part of the problem is Trump's late start, the Journal writes. But part is that fundraising will mean rebuilding some bridges burned during Trump's fundraising-is-bad days.

Another hallmark of Trump's campaign is that he says he will or won't do a thing and then quickly does the opposite. Like Romney, much of the money spent on his behalf may come from outside groups — a new super PAC just announced that it had $32 million to spend — and from the party. Trump may not have fundraising infrastructure, but the GOP does.

One reason this is so important is that Trump's purported electoral strategy isn't cheap. If he wants to win typically Democratic states, he'll need to spend time and money there. In the primary, he could spend a few days in a state right before the election. In the general, every state votes at once, and he can't rely on national media saturation where and when he needs it. So if he wants to try to win California (which he won't) or even just force Clinton to defend safe turf, he'd need to pour money and resources into the state.

In 2008, Obama's fundraising advantage meant that he could explore weird venues for spending, like ads in video games. If Trump trails Clinton by a lot, that sort of extravagance is out of the question — as may be targeting even swing states with saturated attention.

Trump doesn't yet seem to get how the primary differs from the November contest that's just started. He adapted to some degree in order to win the nomination. It's unlikely, though, that the low-cost style of campaigning he used in the primaries will be sufficient to win the general.