This is truly remarkable.

Trump launches a pretty furious attack on the Koch Bros - who are massive GOP donors.  IIRC they were going to be donating US$400 million to the mid-term campaign.  I'd expect many "libertarian" leaning GOP politicians are heavily dependant on Koch contributions.

They must be pulling the pin / turning off the cash flow - and Trump is clearly more than a bit upset.

Background is that they're "objectivist" libertarians, David Koch ran as vice presidential candidate for the Libertarian party.  They believe very strongly in individual liberty (hence are strongly anti-authoritarian), free trade, and open borders if workable. Some people accuse them of being alt-right - but no way, they're closer to for example NZ's ACT party.  The affiliation with the GOP "for convenience" as they're anti-socialist including ideologically against all forms of welfare.

Something's happening behind this.  The Kochs tend to shun publicity - so I don't expect they'll be spilling the beans - but there's a split happening in the GOP, this could be a real problem for Trump.