Three billionaires supplied more than 80 percent of the cash last month for a super political action committee dedicated to derailing Donald Trump. The group is called Our Principles.

February fundraising reports show the Ricketts family — who own the Chicago Cubs and whose patriarch founded TD Ameritrade — gave another $2 million last month, adding to their earlier $3 million investment. Paul Singer, a New York hedge-fund billionaire who backed Rubio, gave $1 million, and Arkansas investment banker Warren Stephens also chipped in $1 million.

OPINION:

I'm a young Chicago Republican. The Donald Trump train doesn't scare me.

The group has reported raising $7.8 million since its inception. FEC documents show the group has spent at least $16 million attacking Trump — so far with little impact. The gap between reported income and expenditures means the majority of the donations to Our Principles arrived this month. Those donors will be disclosed next month.

Talking to the Washington Post editorial board on Monday, Trump pounded on the Ricketts connection and the family's ownership of the Cubs:

HIATT: I'd like to come back to the campaign. You said a few weeks ago after a family in Chicago gave some money to a PAC opposing you, you said, “They better watch out. They have a lot to hide.” What should they watch out for?

TRUMP: Look, they are spending vicious … I don't even know these people. Those Ricketts. I actually said they ought to focus on the Chicago Cubs and, you know, stop playing around. They spent millions of dollars fighting me in Florida. And out of 68 counties, I won 66. I won by 20 points, almost 20 points. Against, everybody thought he was a popular sitting senator. I had $38 million dollars spent on me in Florida over a short period of time. $38 million. And, you know, the Ricketts, I don't even know these people.

HIATT: So, what does it mean, “They better watch out”?

TRUMP: Well, it means that I'll start spending on them. I'll start taking ads telling them all what a rotten job they're doing with the Chicago Cubs. I mean, they are spending on me. I mean, so am I allowed to say that? I'll start doing ads about their baseball team. That it's not properly run or that they haven't done a good job in the brokerage business lately.

The billionaire businessman loaned himself another $6.9 million, bringing the total amount he's loaned to himself to $24.4 million. Trump's campaign manager has said the candidate has no intention of trying to recoup the money he loans himself.

And while Trump continues to boast about self-funding his campaign, he collected about $2 million in new contributions in February, bringing his total raised this cycle to $9.5 million.

He continues to spend big on private airfare, including more than $640,000 to his own airline. And he spent $3.5 million on placed media, including Twitter and Facebook ads.