At the end of a seismic week for the Republicans, Donald Trump now looks the most likely contender to be the party's candidate for the next president of the United States.

Among his big boasts is that he is a modern-day Midas, worth billions of dollars, and that his wealth means that he cannot be bought and sold - and that puts him above the political fray.

But is that the whole picture? Newsnight's John Sweeney reports.