Donald Trump claimed on Friday to have at his disposal “almost $500m in cash”, despite having complained about a $454m bond his lawyers say he cannot pay as he appeals a New York civil fraud judgment.

In an all-capitals, early morning post to his Truth Social platform, the former president said: “Through hard work, talent, and luck, I currently have almost $500m in cash, a substantial amount of which I intended to use in my campaign for president.”

The judge in his New York fraud case knew this, Trump claimed, and therefore came up with a penalty which, with interest, amounts to around $454m.

Trump’s lawyers have said it is a “practical impossibility” for Trump to meet that bond by its 25 March deadline. In turn, the New York state attorney general, Letitia James, reportedly took steps towards seizing Trump-owned properties.

One legal analyst called Trump’s Friday morning rant “the dumbest thing he could possibly have done”.

“That is a direct admission by him that he has the money,” Nick Akerman, a former assistant US attorney in the southern district of New York who was a prosecutor during the Watergate scandal that brought down Richard Nixon, told CNN.

“Keep in mind, even with this operating money or cash that he supposedly has, if he doesn’t pony up and put up a bond, Letitia James is going to be able to go in and basically put restraining orders on all of his bank accounts. Everything that relates to him and all of that money is going to be tied up and frozen.

“So if he’s really got that money, he’s got to put it up.”

As Trump runs to return to the White House, he faces unprecedented legal jeopardy: 88 criminal charges (14 over election subversion, 40 over retention of classified information, 34 over hush-money payments), and various civil penalties – both in the fraud case and in a defamation case arising from a rape allegation a judge called “substantially true”.

Trump’s legal costs are therefore enormous. He received a potential boost on Friday as shareholders approved the public listing of Trump Media & Technology, the parent company of Truth Social, a move that could net more than $3bn. That money, however, will not be accessible for some time and is subject to the whims of the markets.

Also on Friday, multiple outlets reported that Trump’s new fundraising agreement with the Republican National Committee directs donations to his campaign and a political action committee that pays his legal bills before the RNC gets a cut.

The unorthodox diversion of funds to the Save America political action committee – disclosed in an invitation to an event in Florida on 6 April obtained by the Associated Press – makes donors more likely to see their money go to Trump’s lawyers, who have received at least $76m over two years.

Fine print says donations will first be used to give the maximum amount allowed under federal law to Trump’s campaign, which would total $6,600 for individuals giving in a primary and then a general election. Anything left next goes toward a maximum contribution of $5,000 to Save America. Anything more goes to the RNC and state parties.

On the invitation, top donors are asked to contribute $250,000 as “host committee” contributors or $814,600 for a seat at Trump’s table. A separate contribution form allows donors to give contributions of any size but still spells out in fine print that the donation is first to be allocated to the Trump campaign and Save America.

According to the fine print, any donor can direct their contribution to be distributed differently. Donors can also give directly to the RNC or any other entity.

The Trump campaign said donors who contribute the suggested $814,600 or $250,000 per person will see hundreds of thousands of dollars go to the RNC, adding that Save America “also covers a very active and robust post-presidency office and other various expenses”. But the New York Times reported that for smaller events or donations, a much larger share will go to Save America.

It in effect means that when checks are written to the new combined Republican campaign, Trump’s campaign and Save America get paid first.

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With Trump reportedly against declaring bankruptcy, a step that would delay payments in his civil cases but which would likely damage his campaign image, Save America spent more than $50m on legal fees in 2023 and, according to documents filed with the Federal Election Commission (FEC), entered 2024 with just $5m in cash on hand.

The Trump campaign said Save America spends on expenses other than legal fees. But legal spending made up 85% of operating expenses in the first two months of this year, a total of $8.5m.

Trump’s political operation is struggling to catch Joe Biden on fundraising. Trump’s campaign and Save America reported raising $15.9m in February with more than $37m on hand, FEC filings showed. Biden’s campaign raised $53m, with $155m on hand.

On Thursday, a Biden campaign email taunted Trump as “Broke Don”.

Having taken control of the RNC, however, Trump can take advantage of far higher contribution limits. His handpicked leadership team includes his daughter-in-law Lara Trump and Chris LaCivita, one of two campaign managers and now RNC chief of staff.

LaCivita previously suggested the RNC would not pay Trump’s legal bills.

In February, Henry Barbour, an RNC member, attempted to formally preclude such spending, saying: “The RNC has one job. That’s winning elections. I believe RNC funds should be spent solely on winning elections, on political expenses, not legal bills.”

LaCivita said: “The primary is over and it is the RNC’s sole responsibility to defeat Joe Biden and win back the White House. Efforts to delay that assist Joe Biden in the destruction of our nation.”

But with Trump’s RNC takeover complete, Republicans are reportedly concerned it could leave the cash-strapped party shortchanged.

• Associated Press and Reuters contributed reporting