Evan McMullin doesn’t want you to know who his donors are.

The failed Never Trump presidential candidate has stayed in the public eye as a sort of attack dog against President Trump and other Republicans, while keeping secret the names of the donors paying him to do so.

McMullin’s recently founded non-profit organization, Stand Up Republic, jumped into the Alabama Senate race this week with a $500,000 ad buy against Republican Senate candidate Roy Moore. One of the ads features a man saying Roy Moore “makes Republicans and us Christians look bad.”

The massive ad buy “may end up being one of the largest third-party interventions in the state,” according to the Washington Post.

McMullin’s ad campaign against Moore comes as President Trump and the Republican National Committee have jumped back into the campaign on Moore’s behalf.

At his rally Friday night in nearby Pensacola, Florida, Trump told Alabama Republicans to “go out and vote” for Moore. The Post reported McMullin’s massive ad buy the same day.

Because Stand Up Republic is classified as a 501(c)4 “social welfare” group, the organization is allowed to shield the identity of its donors from the public — unlike campaigns and super PACs, which are required by the IRS to disclose the identity of any donor over $200.

“Consistent with existing law, we do not publicly disclose any information about the identities of our donors,” the group’s website states.

Groups like Stand Up Republic are allowed to spend money in elections — which they are doing in Alabama — as long as their “primary” purpose isn’t overtly political. This generally requires spending less than half of the organization’s resources on political activities, although that rule can be difficult to enforce.

McMullin revealed in a tweet last August that his group had “about 4,000 donors across the country from both sides of the political spectrum and larger donors from Silicon Valley.”

One of McMullin’s large Silicon Valley donors is billionaire eBay founder Pierre Omidyar, who funded an anti-Trump super PAC during the presidential campaign.

Omidyar announced a $250,000 donation to Stand Up Republic in May through his organization, Democracy Fund. (Democracy Fund publicizes all its grants in the interest of transparency.)

Democracy Fund said the donation to Stand Up Republic was to support the group in “confronting and engaging in important work to protect the norms of our democracy and to push back against dangerous demagoguery in our politics.”

The identities of McMullin’s other “larger donors from Silicon Valley” remain a secret and he intends to keep it that way.

The Daily Caller made repeated attempts to get answers from Stand Up Republic.

TheDC requested an interview with McMullin and sent a list of questions asking for, if not the identities of Stand Up Republic’s donors, at least details such as how many of the group’s donors have passed certain benchmarks ranging from $1,000 to $1 million. That would at least provide insight into how much of McMullin’s funding is from grassroots supporters and how much is coming from the donor class. But Stand Up Republic declined all of TheDC’s requests.

McMullin, who woefully underperformed as a spoiler candidate, has managed to stay somewhat relevant by launching frenzied attacks on President Trump and his allies.

McMullin has repeatedly accused the president of being a traitor who is loyal to Russia over the United States, despite lacking any proof for that claim.

A month after the 2016 election, McMullin declared that “Donald Trump is not a loyal American and we should prepare for the next four years accordingly.”

He has maintained that line of attack on the president, and just last week claimed Trump “remains loyal” to Russia.

McMullin hasn’t just targeted Trump, though. He railed against Ed Gillepsie, the Republican candidate for governor in Virginia, for his tough-on-crime approach to gang violence.

McMullin, citing no evidence, claimed that Gillepsie was peddling “white nationalism,” and said that he was rooting for the Republican candidate to lose.

McMullin’s consistent, biting criticisms of the president and other Republicans have made him a semi-regular guest on MSNBC — but at the cost of disgusting some of the people who helped legitimize him.

Some of his former backers have issued public apologies for ever supporting him.

But even as McMullin alienates some of the few conservative allies he had, it remains unclear who is paying him to do so.