Joe Biden says if elected president he'll ban holding of positions with foreign companies by family members and those associated him, a definition that covers hundreds of people from his 44 years in national office.

“No one in my family or associated with me will be involved in any foreign operation whatsoever. Period. End of story," the former vice president and 36-year Delaware senator said at an Altoona, Iowa, campaign event.

The declaration by Biden, 76, comes after torrents of criticism about his son Hunter Biden by President Trump over his position on the board of a Ukrainian natural gas company. The $50,000-a-month role began in 2014 at the same time his father, the vice president, played a lead role in the Obama administration's Ukraine policy.

Hunter Biden, 49, is a frequent target of Trump on Twitter, at campaign rallies, and other forums, repeatedly calling the Biden father-son due "corrupt." Trump, in a July 25 phone call, leaned on Ukrainian President Volodymyr Zelensky to investigate Hunter Biden's work in that country, with U.S. military aid dangled as leverage. That exchange is now at the heart of an impeachment inquiry against Trump by House Democrats.

Democrats vying for the 2020 presidential nomination against Biden have been pressed on whether they would permit family members of their vice presidential pick to sit on foreign boards. Most have said no, though they've demurred from directly attacking Biden over the issue.

Hunter Biden has also been criticized for his business dealings in China. On Sunday, the 49-year-old's lawyer George Mesires announced his client was stepping down from the board of BHR (Shanghai) Equity Investment Fund Management Company. BHR is a private equity firm backed by Chinese state-owned financial companies and whose largest shareholder is the state-controlled Bank of China.

Joe Biden, on the sidelines of United Food and Commercial Workers' presidential forum in Altoona, Iowa, said the younger Biden "could" have continued in the role.

"He has decided that he does not think that is good to do. He has said that he does not like appearance of it," Biden said. "I've never discussed this with my son while I was vice president, or since being vice president, except in the recent past when I was told by his lawyers that he is going to be issuing a statement."