Jeb Bush's team has told many deep-pocketed donors not to give above $1 million to his Super PAC in this fundraising quarter, reports the Washington Post's Matea Gold . Team Bush would, however, be happy to accept the money later on. It's the latest sign that Bush's fundraising has been phenomenally successful — a huge point in his favor in the invisible primary , and one likely to solidify his position as the GOP's presidential frontrunner.

Jeb Bush is raising an absurd amount of money

So why is Bush's team telling donors to chill out? There are a few possible answers. Gold suggests that they're concerned "that accepting massive sums from a handful of uber-rich supporters could fuel a perception" that Bush is "in their debt," and that they want to make sure not to rely too much on money from a very small group of people. The latter is a particularly interesting point — if Bush is raising huge sums from a relatively small amount of people, it suggests that hasn't locked down Republican and conservative support yet.

Another possible reason involves the optics of fundraising. Though there are no limits on how much money a donor can give to a Super PAC, there are obviously personal limits in how much each donor is comfortable giving overall. So Bush may worry that if his donors are tapped out too quickly, his fundraising performance in future quarters would look weak.

Still, this is definitely a good problem for Bush to have. He's clearly been on a fundraising roll. For instance, the Wall Street Journal's Patrick O'Connor reported that donors who want to join the official "top tier" will have to raise $500,000 by the end of this month. But, O'Connor added, many "expect it will cost significantly more to reach the inner circle of an expected Bush campaign because deep-pocketed donors have been so eager to write big checks." And tickets to a well-attended recent New York City Bush fundraiser cost $100,000 each, Politico's Ben White reported.

Money certainly won't be sufficient to hand Bush the nomination — questions about his appeal to the conservative base and actual voters remain — but this fundraising will certainly allow Bush to get his message out, and seems to position him as the man to beat.