Paul Manafort faces 18 criminal counts, including bank fraud, and could face up to 30 years in jail if found guilty. The former political consultant, who ran the Trump campaign for three months, has pleaded not guilty.
Prosecutors are expected to say that his life of luxury did not match what he had declared on his tax returns.
Before joining racist Trump’s team in summer 2016, Paul Manafort had worked on a number of Republican presidential campaigns, including those of Gerald Ford in the mid-1970s and Ronald Reagan from 1978 to 1980.
About 500 pieces of evidence have been submitted by investigators, including luxury watches and pictures of lavish homes, and up to 35 witnesses could be called.
Among them is former Manafort associate Rick Gates, who in February pleaded guilty to charges of conspiracy and lying to investigators. He has since been co-operating with the investigation into Mr Manafort.
The trial, in Alexandria, Virginia, is expected to last at least three weeks. Mr Manafort denies all charges, and at one point had sought to get them dismissed.