The ACORN-connected, union-supported Working Families Party, which had been under federal investigation for eight months, declared yesterday that it was finally off the hook.

“We were advised . . . that the US Attorney’s Office has decided to close its investigation without the filing of any charges,” spokesman Dan Levitan said in a statement.

The US Attorney’s Office declined comment.

The investigation, announced in December, targeted Data & Field Services, the WFP’s for-profit consulting firm, for allegedly charging candidates lower-than-usual fees in 2009 city elections.

The probe made state Attorney General and gubernatorial candidate Andrew Cuomo, a Democrat, nervous enough to back away from the party’s endorsement.

The WFP was created 10 years ago with backing from ACORN, the left-leaning organization that came under fire after some of its workers were caught instructing a man posing as a pimp on how to cheat on his taxes.