An Air Force veteran racked up millions more dollars on his fundraising page for President Donald Trump's U.S.-Mexico border wall, but it remained unclear Friday how the U.S. government would get the money.

Brian Kolfage's GoFundMe page has raised more than $13 million as of Friday afternoon to build the wall, whose funding was threatening a partial government shutdown. The crowdfunding page, which was launched less than a week ago, has a goal of $1 billion.

In a statement on the page, Kolfage assured contributors that the fundraiser was not a scam and that he had contacted the Trump administration about how to deliver the money.

White House officials did not immediately return an email seeking comment Friday.

Citizens can mail money as "gifts to the United States," according to the U.S. Treasury Department. But it's not clear whether the Department of Homeland Security can accept gifts.

Kolfage of Miramar Beach, Florida, wrote that donors would get a refund if the fundraising goal isn't met.

The page has brought attention to Kolfage, a triple amputee who was wounded in the Iraq War in 2004, and his social media history.

NBC News reported that Kolfage operated a Facebook page called "Right Wing News" and sites that promoted conspiracy theories. He told the news outlet that he didn't mention the page because he "didn't want it to be a distraction."

"That shouldn't be the focus. My personal issues have nothing to do with building the wall," Kolfage said.

He told The Associated Press in an email Thursday that he worked on "Right Wing News" but the rest of NBC's story "is not true."

Kolfage did not respond Friday to multiple requests for comment from the AP.