WASHINGTON — President Trump on Wednesday questioned the origins of a leaked tax return that showed he paid $38 million on more than $150 million of reported income in 2005 — while the recipient of the leak suggested it may have come from Trump himself.

"Does anybody really believe that a reporter, who nobody ever heard of, 'went to his mailbox' and found my tax returns?" Trump tweeted the morning after MSNBC disclosed two pages of the 2005 return. "@NBCNews FAKE NEWS!"

David Cay Johnston, a Pulitzer Prize-winning journalist who wrote a book about Trump and founded the website DCReport.org, told MSNBC's Rachel Maddow Show that he obtained two pages of Trump's 2005 tax return via the U.S. mail.

Johnston — who told Maddow that "it's entirely possible that Donald Trump sent this to me; Donald Trump has, over the years, leaked all sorts of things" — responded in kind on Twitter: "Gee, Donald, your White House confirmed my story. POTUS fake Tweet. Sad!"

The author of a book called The Making of Donald Trump also said Wednesday that he and his family have received death threats since the tax story broke.

Trump, who refused to release any of his taxes during the 2016 campaign, wrote off more than $100 million in business losses for 2005, and paid the alternative minimum tax. The president has proposed eliminating the AMT, a move that would lead to lower tax bills for him and other wealthy Americans.

His $38 million payment in 2005 reflected a 25% tax rate.

Critics say Trump's tax returns could shed light on the investigation into Russian activities during the 2016 presidential election. Trump has called the Russia investigation a "witch hunt" and said he has no business interests in Russia.

The two pages of 2005 tax returns that emerged this week shed no light on the issue. "This describes the types of income, but not the sources,” Johnston told MSNBC.

The president and aides have not said whether he will release his next tax return, as previous presidents have done.

The White House statement, while confirming the numbers in the return, questioned the legality of the leak.

"The dishonest media can continue to make this part of their agenda, while the President will focus on his, which includes tax reform that will benefit all Americans," the statement said.

During his morning tweetstorm, the president also protested a new music video by the rapper Snoop Dogg, who is seen shooting a Trump-like figure.

"Can you imagine what the outcry would be if @SnoopDogg, failing career and all, had aimed and fired the gun at President Obama?" Trump said. "Jail time!"