The UK Telegraph has done an exclusive investigation:
Donald Trump’s presidential campaign is facing a fundraising scandal after a Telegraph investigation exposed how key supporters were prepared to accept illicit donations from foreign backers.
The Telegraph did their own version of James O’Keefe (except competently), going undercover and pretending to represent a Chinese donor:
Undercover reporters posing as consultants acting for a Chinese benefactor approached specific pro-Trump and pro-Clinton fundraisers and groups after receiving information that individuals were involved in hiding foreign donations.
The Clinton camp didn’t return their calls. Trump’s people, however, were interested:
But earlier this month an undercover reporter spoke by telephone to Eric Beach, co-chairman of the pro-Trump Great America PAC, which has the backing of Rudy Giuliani, one of Mr Trump’s most senior advisers, as well as the billionaire's son Eric.
...
Mr Benton said the $2 million, for which he would submit an invoice for “appearances” would “definitely allow us to spend two million more dollars on digital and television advertising for Trump.” The Chinese benefactor's generosity would be “whispered into Mr Trump’s ear.” He said he had previously helped US donors conceal donations.
The whole story is rather sordid, and should be read in its entirety.