Reid Hoffman is putting his money where his mouth is. On Monday, the LinkedIn co-founder became the latest Silicon Valley leader to go after Donald Trump, pledging to donate up to $5 million to veterans groups if the Republican presidential nominee releases his tax returns. “There’s no real reason that Trump is keeping his returns secret, except that he sees them as a bargaining chip to utilize,” Hoffman wrote in a Medium post. “As Trump skirts his obligation to the American people, we must show him that we do value accountability and transparency.”

Hoffman, whose own net worth grew by $800 million in one day this year when Microsoft bought LinkedIn for $26 billion, explained that he would be supporting a Crowdpac.com campaign started by 26-year-old U.S. Marine Corps veteran Peter Kiernan, who is crowd-funding money to to donate to 10 different veterans organizations if Trump releases his tax returns. “To be clear, raising and donating this money to veterans groups will not cost a penny to Donald Trump, just the release of his tax returns,” Kiernan writes on his crowd-funding page. “So what do you say Mr. Trump, can you walk away from this deal?”

Trump, of course, has insisted on keeping his tax returns private, citing an I.R.S. audit. But if that changes, and Kiernan’s campaign meets its $1 million goal by October 19, the date of the final presidential debate, and Trump releases his tax returns, Hoffman says he will donate as much as $5 million. The $5 million Hoffman is willing to donate, he says in his post on Medium, is the same amount that Trump said he’d donate in 2012 for the release of President Barack Obama’s college records and passport documents. “Given Trump’s vocal support of veterans, I imagine he will recognize the great good that can come from Kiernan’s proposal,” Hoffman says. “But taking Trump’s own 2012 offer to President Obama into account, I’d like to assist Kiernan in his campaign.”

Hoffman was an early independent investor in Crowdpac—he’s been involved in other Crowdpac campaigns before, and he stands to profit from the success of the platform. Still, it’s a public wager against Trump that unites Hoffman with other leaders in Silicon Valley, most recently including Facebook co-founder Dustin Moskovitz, who last week pledged $20 million to Democratic organizations to fight Trump’s White House bid. “The Republican Party, and Donald Trump in particular, is running on a zero-sum vision, stressing a false contest between their constituency and the rest of the world,” Moskovitz wrote in his own Medium post. This summer, a group of 145 Silicon Valley executives, founders, and venture capitalists converged to sign an open letter condemning the idea of a Trump presidency, which would be “a disaster for innovation,” they argued. Clinton counts Silicon Valley executives including Marc Benioff, Sean Parker, Eric Schmidt, Sheryl Sandberg, Airbnb C.E.O. Brian Chesky, and Netflix C.E.O. Reed Hastings among her supporters. Trump, on the other hand, is most famously flanked by just one prominent Bay Area leader: “PayPal Mafia” alum and early Facebook investor Peter Thiel, who was a Trump delegate and made a speaking appearance at the R.N.C. this summer, though he is not fundraising for the candidate.