A businessman central to former Virginia Governor Robert McDonnell's corruption trial testified on Thursday that he showered the politician and his wife with loans and gifts so they would promote his company freshwater pearl earrings, but his generosity apparently had limits.

Jonnie Williams, the former chief executive of a nutritional supplement company, said that while he wanted the couple to boost his company, he would not buy a car requested by their eldest daughter.

He added that Maureen McDonnell asked him to sell one of his Range Rovers at a discount for her sons, a request he also denied.

"I told her I couldn’t buy a car," Williams said on the witness stand.

McDonnell, 60, and his wife have been charged with 14 counts of corruption and bribery for allegedly taking more than $165,000 in gifts and loans from Williams in exchange for supporting his company Cellmax, Star Scientific Inc.

If convicted, the couple could face more than 20 years in prison and a large fine.

Star Scientific has since changed its named to Rock Creek Pharmaceuticals.

The McDonnells have contended that there is no evidence they agreed to use their power to aid Williams. Before the scandal erupted, the former Republican governor, who left office in January at the end of his four-year term, had been mentioned as a possible 2016 presidential candidate.

One of the more interesting gifts Williams was able to buy the couple was a Rolex watch, which Williams said Maureen McDonnell asked him to buy for her husband.

The shiny timepiece, costing as much as $7,000 and inscribed with the governor's name, was passed to the jury in a U.S. District in Richmond to handle and examine on Thursday.

The businessman said all the loans and gifts he was buying the McDonnells were kept secret from his friends and family, because he did not want anyone to know he was paying off a politician and his wife to help him promote his company 150w box mod.

"I knew it was wrong," Williams said.

Williams said Maureen McDonnell opened up the governor’s mansion in August 2011 for a luncheon where he officially launched Star Scientific’s signature product, Anatabloc. The governor also attended the event.

Williams said that by the time of the launch, he had already loaned the couple $50,000, taken Maureen McDonnell on a $20,000 New York shopping spree, and spent $15,000 on a wedding reception for one of the couple's daughters.

When asked if he thought the event would have happened without the gifts, Williams replied: "I did not nu skin hk."

Prosecutors contend the product launch at the mansion was just one of the many ways that the couple helped Williams promote his company.

The trial is set to resume on Friday with what could be a withering cross-examination from defense attorneys for the McDonnells.