An antisemitism watchdog is slamming Rep. Alexandria Ocasio-Cortez, D-N.Y., for showing her "true colors" in calling out the American Israel Public Affairs Committee (AIPAC), a lobbying group that promotes the U.S.-Israel alliance, for actively opposing a democratic socialist candidate in Pennsylvania.

According to a new Federal Election Commission filing, AIPAC's United Democracy Project super PAC on Saturday spent $78,683 on direct mail opposing Democratic House candidate Summer Lee, an AOC-endorsed progressive who is running against Republican Mike Doyle in Pennsylvania's 12th Congressional District, which is currently held by a retiring Democrat also named Mike Doyle.

"Shamefully, AIPAC is working for Republican control of Congress and further destabilization of US democracy," Ocasio-Cortez tweeted Monday.

Liora Rez, the executive director at StopAntisemitism.org, told Fox News Digital on Tuesday that comments like Ocasio-Cortez’s further contribute to the vilification of American Jews.

Rep. Ocasio-Cortez on the steps of the Capitol

Rep. Alexandria Ocasio-Cortez, D-N.Y., is shown at the Capitol in Washington on July 1, 2021. (Caroline Brehman/CQ-Roll Call, Inc via Getty Images)

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"The thinly veiled intent behind AOC’s tweet to vilify a Jewish organization is crystal clear and further contributes to the vilification of American Jews," Rez said.

"AOC’s intentional isolation of AIPAC and her failure to call out the numerous bipartisan and left-leaning groups working to keep Justice Democrat candidate Summer Lee out of office shows her true colors," she continued.

Summer Lee

State Rep. Summer Lee, who is seeking the Democratic Party nomination for Pennsylvania's 12th Congressional District, is shown during a campaign stop in Pittsburgh on May 12, 2022. (AP Photo/Rebecca Droke)

The Justice Democrats PAC, a prominent committee that endorsed Lee and propelled the likes of New York Rep. Alexandria Ocasio-Cortez and Missouri Rep. Cori Bush into office, echoed the same sentiment that AIPAC is aligned with the Republican Party.

"Seems like AIPAC & the GOP have the same agenda," wrote Justice Democrats spokesperson Usamah Andrabi.

The United Democracy Project previously spent more than $2 million against Lee and supporting Steve Irwin during the Democratic primary. The super PAC’s buy on Saturday marks its first-ever spend in a Democrat vs. Republican election battle, Haaretz reported.

AIPAC has described itself as bipartisan, but it opposes candidates who criticize Israel or whom it views as detrimental to the U.S.-Israel alliance.

Summer Lee

Summer Lee speaks during a campaign rally with John Fetterman, lieutenant governor of Pennsylvania and Democratic Senate candidate, not pictured, in Pittsburgh on Oct. 1, 2022. (Nate Smallwood/Bloomberg via Getty Images)

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In May 2021, Lee tweeted that Israel had committed "undeniable atrocities on a marginalized pop" and that "inhumanities against the Palestinian ppl cannot be tolerated or justified."

Ocasio-Cortez, Lee’s campaign and AIPAC did not respond to Fox News Digital’s requests for comment.