Queens Democrat John Liu will be endorsed endorsed by a trio of influential members of Congress on Monday as he seeks to unseat Independent Democratic Conference Sen. Tony Avella in a primary.

Liu, a former New York City comptroller is being supported by Reps. Joe Crowley, Grace Meng and Gregory Meeks — three Queens lawmakers who represent key constituencies.

“John Liu has served this city with distinction. His record, unwavering commitment and relentless energy is second to none,” said Crowley, the Queens Democratic chairman, in a statement. “For the people of Senate District 11, of Queens and of New York City, the choice is clear. The fiscal expertise and legislative experience John Liu offers and will bring to the Senate on behalf of his constituents will deliver unparalleled results. He’s by far the best choice in the Democratic primary to stand up for our values and bring every community together.”

Meeks cited Liu’s “unwavering commitment to justice and equality” as his reasons for supporting his primary.

“No one will work harder to bring results to our community than John Liu,” Meeks said. “On issue after issue, John Liu has been a strong champion for all New Yorkers. We need his leadership now more than ever.”

Meng added Liu is an “outstanding public servant.”

“His experience as our Comptroller and as a Queens Councilman make him well prepared to tackle the important issues in Albany, and I look forward to working with him to make our city, state and borough an even better place to live,” she said.

Liu launched his primary bid earlier this year, which came as mainline Democrats sought to challenge members of the five-member Independent Democratic Conference in primaries.

But several of those potential challenges fizzled after the IDC and mainline conference agreed to form a new coalition after Election Day this year, ending the independent Democrats’ governing agreement with Senate Republicans.

Liu’s primary bid, however, hasn’t been curtailed as he has wrapped up multiple labor endorsements as well.

The labor-backed Working Families Party earlier agreed to remain neutral in the race, along with the primary bid by Oliver Koppell, who is challenging IDC Leader Jeff Klein.