Paul Ryan (not that one), of the nonpartisan nonprofit Campaign Legal Center, said that Trump would have to forgo accepting royalties for sales on the book in order for the transaction to be legal, under Federal Election Committee rules.

“It’s fine for a candidate’s book to be purchased by his committee, but it’s impermissible to receive royalties from the publisher,” Ryan said. “That amounts to an illegal conversion of campaign funds to personal use. There’s a well established precedent from the FEC that funds from the campaign account can’t end up in your own pocket.”