Story highlights Donald Trump is asking vice presidential candidates for their tax returns

That's even though he himself is not willing to share his

Washington (CNN) Donald Trump is asking vice presidential hopefuls for their tax returns -- even though he is not yet releasing his.

It is standard practice for potential vice presidential picks to submit detailed financial paperwork, including tax returns, to the person who could choose them to serve as their No. 2 in the White House. But it would be unprecedented in modern times for that vice president to be the only one on the ticket who has disclosed theirs.

A Trump adviser confirmed Wednesday that presumptive Republican presidential nominee will require the men and women he is considering for his vice president to submit them to his vetting team. The VP nominees' records wouldn't be made public. Trump, meanwhile, has said he will only release his when his routine audits come to a close -- something he admits could come after Election Day.

Trump's resistance to publicly releasing his tax documents leaves major questions for voters weighing a candidate whose campaign is staked on his business acumen and the fact that he says he is "very, very rich" -- and would mark a major break with decades of precedent set by the nominees of the two major political parties.

Trump has maintained that there is little that people could learn from his returns. He has said that "I fight like hell not to pay" much in taxes, but he has declined to release the rate in advance.

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