Democratic online fundraising platform ActBlue should be investigated for potentially supporting terrorist groups following “credible allegations” of fraud, a Republican lawmaker has argued this week.

Rep. Darrell Issa (R-Calif.) fired off a letter to the Treasury Department on Tuesday urging the Trump administration to investigate whether ActBlue, which has funneled billions of dollars to Democratic candidates in recent election cycles, has knowingly accepted payments from any terror-linked groups.

“I write to raise concerns regarding the progressive fundraising organization ActBlue – as well as its charitable arm ActBlue Charities – and credible allegations of the provision of fundraising services and payment processing for terror-linked organizations and nonprofits,” Issa wrote.

“As mounting evidence of ActBlue’s dangerous corruption piles up, it is imperative that the Department of the Treasury investigate whether ActBlue Charities had reason to know it was handling payments that could support terror.”

Issa, who is vice chairman of the House Foreign Affairs Committee, specifically noted ActBlue’s ties to the Palestinian Campaign for the Academic and Cultural Boycott of Israel, as well as the US Campaign for Palestinian Rights — the latter of which is backed by left-wing billionaire George Soros.

“Neither ActBlue Charities – nor its parent organization ActBlue – have any reliable process to vet users of their platforms for links to terrorism, simply ignore their obligations under the law, and are actively abetting this collaboration,” Issa wrote in the letter, obtained by The Post Wednesday and first reported by the Free Press.

“Terror financing is an extremely serious crime, and organizations cannot be given a free pass for failed due diligence, or worse, the enabling of terrorism.”

In addition to enabling alleged terrorism, Issa claimed that collaboration between ActBlue and the two entities “may also constitute money-laundering crimes.”

“In addition, the flagrant inability of progressive groups to address the appearance of skirting a full range of our laws — or call out the evils of Hamas and the BDS movement — raises critical questions if the activities and coalition building of ActBlue and ActBlue Charities are in reality part of a wider commitment to financing and facilitating attacks on Israel and Jewish people in America and around the globe,” he said.

A senior aide to the California Republican indicated to The Post that the letter marked the beginning of a full probe into ActBlue and ActBlue Charities after the Biden administration thwarted previous attempts.

Issa’s letter comes just days after House Republicans renewed their demands for data from the Treasury Department to determine whether fraudulent campaign contributions were made from “dummy” small-dollar donors to the platform.

Before last year, ActBlue did not require donors to input their Card Verification Values (CVVs) when making online contributions — potentially opening the door to “identity theft and fraud,” according to a letter Reps. James Comer (R-Ky.), Bryan Steil (R-Wis.) and Nick Langworthy (R-NY) sent to Treasury Secretary Scott Bessent on Monday.

“The organization is also the subject of several state-level investigations stemming from allegedly fraudulent contributions made via the platform without the reported contributors’ awareness — serious allegations that, if proven true, would violate federal law,” the Republican lawmakers added.

Some of those fraudulent contributions could have come from foreign nationals, the Republicans also noted, which would violate federal campaign finance law.

A memo obtained by The Post in October revealed Treasury officials had discovered “hundreds” of Suspicious Activity Reports (SARs) apparently linked to ActBlue donors.

Comer, who chairs the Oversight panel, and Steil, who chairs the Administration Committee, have requested all suspicious transaction reports linked to the lefty fundraising juggernaut dating from Jan. 1, 2023.