Donald Trump checked the box on his tax returns to support public campaign finance

This may come as a surprise, but President Donald Trump isn't a typical Republican.

This week, two pages from a single Trump tax return from 2005 was leaked by mail to a Pulitzer Prize-winning journalist, possibly by the president himself. For over a year, the media have been asking Trump for his tax returns, which candidates typically turn over prior to an election.

The document held few surprises. Trump made more than $150 million in 2005 and paid about 25 percent in taxes largely due to the alternative minimum tax. But one minor detail is interesting: On this return, Trump supported public financing of elections by checking the often-overlooked box on his 1040 form.

The Presidential Election Campaign Fund provides public campaign financing for candidates willing to follow the program's strict rules and spending limits. The fund was created after the Watergate scandal and has supported nearly every campaign since then.

In 2008, President Barack Obama became the first general election candidate to turn down the funding, despite an earlier pledge to take it. In the last general election, neither major party candidate accepted the money.

Checking the box on a tax return doesn't cost the filer a thing — it just directs the IRS to move $3 into the fund. Still, fewer and fewer Americans check the box each year — only about 6 percent elected to support the fund last year.

Even politicians with plans to take public money may not opt to keep it well-funded. Ronald Reagan took $37 million from the fund in 1980 (more than half his funding), and $50 million in 1984, but he declined to support the fund on every tax form he released. George W. Bush also accepted millions from the fund without checking the "yes" box.

Generally, recent Republican candidates have been less inclined to check the box, while Democrats are more friendly to the fund. Although we have only one year to go by, Trump seems to be an exception to that trend, along with Ted Cruz, Mitt Romney and John McCain. Trump didn't take public money, despite being in the unique position of needing it in the middle of his campaign.

"I don't like the idea of taking taxpayer money to run a campaign," Trump told the AP in May. "I think it's inappropriate."

While the public campaign finance of today is generally considered inadequate to meet the financing needs of a modern election, the idea of freeing candidates from fundraising and political interest groups has historically received support from both sides of the aisle.

It was Republican President Theodore Roosevelt who first proposed a public financing fund, in his 1907 State of the Union speech.

"The need for collecting large campaign funds would vanish if Congress provided an appropriation for the proper and legitimate expenses of each of the great national parties," he said. "An appropriation ample enough to meet the necessity for thorough organization and machinery, which requires a large expenditure of money."

John F. Kennedy raised the idea again in 1960, but his proposal was blocked by Congress. Lyndon Johnson instituted the Presidential Election Campaign Act in 1966, which was deactivated by Democratic senators and then revived again by Democrats in 1973. The modern system was set up in 1974 after Watergate.

Recently, Republicans have pushed back on the fund, pointing out that its restrictions make it nearly irrelevant. Jeb Bush called public finance "welfare for politicians" and campaigned against it, despite supporting it on his taxes at least once. In the last election, only Martin O'Malley and Jill Stein took public funds, leaving the majority of the money untouched.

The White House did not immediately respond to a request for comment.