Big Democratic donors are going to bat for Sen. Joe Manchin’s endangered re-election campaign, using a new political nonprofit to carpet bomb West Virginia with television advertising.

Duty and Honor, a 501(c)4, has invested nearly $500,000 so far to support the vulnerable incumbent in a state that is overwhelmingly supportive of President Trump, according to a Federal Election Commission filing. Political nonprofits can raise money in unlimited amounts, and do not have to publicly disclose their donors.

“Joe Manchin was one of three Democrats to vote with President Trump to fund the wall,” the voiceover in the Duty and Honor spot says. “The fact is, Joe is one of us.”

Manchin, facing a stiff challenge from West Virginia Attorney General Patrick Morrisey, a Republican, also is benefiting from air cover from Duty and Country, a super PAC. Last week, that group reported $80,000 in independent expenditures for digital advertising for Manchin — half positive spots to boost the senator and half negative ads to undermine Morrisey.

Manchin is one of the Republican Party’s top targets in the midterm elections. For years a popular political figure in West Virginia, the GOP is confident in Morrisey’s prospects because the state has moved further and further away from the Democratic Party over the years. Trump won the state by 42 percentage points in 2016, and Manchin has tended to oppose the president’s agenda in his votes on the Senate floor.

Manchin this past week was critical of Trump’s since-abandoned zero tolerance policy that resulted in splitting families apprehended illegally crossing the Southern border with Mexico. The policy sparked a national political uproar that left Republicans panicking it could sink the their congressional majorities.

Manchin signed onto a bill proposed by Sen. Dianne Feinstein, D-Calif., to halt the separations policy. But Republicans are backing a more conservative proposal to end family separations, and Morrisey saw an opening to paint Manchin as a too lenient on illegal immigration — and pounced.

“Joe Manchin is clearly deceiving West Virginia voters about his radical open-borders record, and his support for the Obama-era catch-and-release policies in the Manchin-Feinstein border bill,” Morrisey spokesman Nathan Brand said.

Senate Majority PAC, aligned with Senate Minority Leader Chuck Schumer, D-N.Y., is the main Democratic super PAC spending money to defend vulnerable Senate incumbents.

But with the party’s reputation diminished in West Virginia, its possible that wealthy Democratic donors could channel their support for Manchin through Duty and Country, the super PAC, and Duty and Honor, a political nonprofit under federal law that is limited in how much overt political activity it can engage in.

Republican operatives active in the West Virginia Senate race are hoping to undercut the groups’ effectiveness by suggesting that their financial backing comes from Democratic donors who do not share Trump’s hawkish immigration agenda.

One Republican strategist, trying to cause Manchin problems with his Democratic base, forwarded an interview he conducted in which he lamented the influence of so-called “dark money” groups in American politics. Liberal activists have demanded campaign finance reform to outlaw such groups.

“A lot of donors can remain secret, so people don't know who's behind certain attacks. No one can be held accountable or responsible. And that's just wrong,” Manchin said last year in an interview with progressive journalist Cenk Uygur.

