Story highlights Donald Trump Jr. spoke about his father's voluminous tax returns

He said releasing the returns would lead to questions that would detract from his father's message

Washington (CNN) Donald Trump's son has a new reason to explain why his father won't release his tax returns: They'll steal from his political message.

"Because he's got a 12,000-page tax return that would create ... financial auditors out of every person in the country asking questions that would detract from (his father's) main message," Donald Trump, Jr. told the Pittsburgh Tribune-Review in a piece published Wednesday.

That's a dramatic shift from the Republican nominee's longtime explanation that an ongoing audit is preventing him from releasing his tax returns. (There are no laws barring Trump from disclosing his tax returns while he is being audited).

The comment reflects the political potency of Trump's tax returns. There are growing questions about what's in the documents, including details of investments in foreign countries. House Speaker Paul Ryan, who was the GOP's vice presidential nominee in 2012, said Thursday that presidential candidates should release their tax returns.

"I released mine," Ryan said. "I think we should release our returns. I'll leave it to him when to do it."

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