Two of Sen. Bernie Sanders's (I., Vt.) top advisers have deep ties to the anti-Israel community and were chastised several years ago for their involvement in an anti-Semitism scandal that gripped a prominent Washington, D.C., think-tank.

Sanders, a self-proclaimed Democratic-socialist who has once again thrown his hat into the ring for a 2020 presidential bid, has begun to rely in recent months on two staffers: Foreign policy adviser Matt Duss and campaign manager Faiz Shakir, both of whom faced charges of promoting anti-Semitic conspiracy theories during their time at the Center for American Progress, or CAP, a liberal think-tank.

Sanders's dependence on Duss and Shakir has been making waves in the pro-Israel and Jewish community in recent months, given the duo's prominent role in CAP's 2012 anti-Semitism row, which saw several staffers at the organization's Think Progress blog rebuked for invoking age-old canards about Jewish control of money and politics. Duss has faced additional scrutiny in the subsequent years for publishing Nazi-era propaganda posters and steadfastly standing against the U.S.-Israel alliance

As the matter of anti-Jewish bias in prominent D.C. political circles makes its way back into the news following a series of anti-Semitic comments by freshman Rep. Ilhan Omar (D., Minn.), many in the pro-Israel community are beginning to raise questions about Sanders' choice to fill his ranks with individuals closely tied to some of the most prominent anti-Israel causes.

In 2012, Duss was CAP's Middle East director, while Shakir served as editor-in-chief of the group's Think Progress blog, which has since become regarded as a hotbed for anti-Israel activism.

During their tenure at CAP, Duss and Shakir emerged at the forefront of a scandal involving several Think Progress bloggers who accused pro-Israel Jews and members of Congress of being "Israel firsters," a term implying that those who support the Jewish state have dual loyalties.

The scandal rocked CAP for several months and drew condemnation across the board, including from the Obama administration, which distanced itself from Duss, Shakir, and the rest of Think Progress's former staff.

Shakir—who initially remained silent as controversy swirled around Think Progress's use of anti-Semitic language—later said in a leaked internal email that his employees used "terrible, anti-Semitic language" when invoking the "Israel firster" term.

Duss also stood on the sidelines at the time, declining to condemn the anti-Semitic language. Numerous articles penned by Duss and other CAP Action Fund bloggers were said "to be infected with Jew-hatred and discriminatory policy positions toward Israel," according to the Simon Wiesenthal Center, which combats anti-Semitism.

Duss, who was recently hailed as the "progressive" foreign policy mind behind Sanders, has for the better part of the last decade been a driving force behind the far left's anti-Israel activism. Oftentimes, this criticism waded into anti-Semitic waters.

In 2013, for instance, after the "Israel firster" scandal ended with the firing and departure of several Think Progress bloggers, Duss again was charged with anti-Semitism after he published Nazi-era propaganda posters online as part of a campaign to discredit a conservative Israeli advocacy organization.

"Given CAP's disturbing familiarity with, and history of, deploying what leading global anti-Semitism experts and watchdog organizations identified as actual anti-Semitic language, it is both ironic and troubling to see CAP's Matt Duss dubiously objecting to imagery that is not being described as such by such experts in his transparent attempt to smear those with whom he disagrees," one senior Jewish community official told the Washington Free Beacon at the time.

A Free Beacon report conducted at that time linked several other members of Duss’s family to vitriolic activism against the Jewish state.

Meanwhile, Shakir also returned to the anti-Israel stage after departing from CAP.

As national political director for the American Civil Liberties Union, or ACLU, Shakir led the charge to kill a major piece of pro-Israel legislation aimed at thwarting boycotts of Israel.

Shakir and a colleague penned a Washington Post editorial in 2017 in which they argued that congressional efforts to impede the Boycott, Divestment, and Sanctions movement, or BDS, a global campaign to wage economic warfare on Israel, impeded free speech rights.

This argument has been thoroughly debunked by prominent members of Congress and the pro-Israel community as a whole.

Multiple sources from across the pro-Israel and Jewish worlds who spoke to the Free Beacon both on the record and only on background emphasized that Sanders' promotion of both Duss and Shakir is not going unnoticed.

"Sanders is building a campaign team filled with people who have devoted their careers to running anti-Semitic campaigns and calling them anti-Israel," said one veteran Jewish communal activist. "It's deliberate and transparent. These are people who take over progressive organizations and turn them into hubs for pushing and defending open hostility toward Israelis and Jews. It's clearly what they're being hired to do now."

"Sanders used to leave foreign policy alone, but now he's found advisers to sharpen his message for the progressive zeitgeist," said Noah Pollak, a veteran Republican consultant and executive director of the Committee for Israel. "The zeitgeist, and those advisors, are obsessed with Israel, and the reason they're obsessed with Israel is because they appear to be obsessed with Jews. It's appalling on the substance but it's also bad politics. Most of America is going to be puzzled to discover, to take one example, that a few months ago during Hamas's attempts to send terrorists across Israel's border, Sanders was on TV repeating Hamas talking points about peaceful protesters. Sanders's domestic policy amounts to hating the rich and his foreign policy amounts to hating Israel. It's probably not a winning platform."

Josh Block, a longtime Democratic strategist who first brought the CAP scandal to the public forefront, condemned Sanders for bringing Duss and Shakir into his political orbit.

"In a climate of escalating Jew-hate, particularly coming from self-described progressives, it is especially alarming that Bernie Sanders would put in charge of his presidential campaign and foreign policy portfolio two people so deeply at the heart of an anti-Semitism scandal and cancer that had to be cut-out from the Center for American Progress for engaging in vile Jew-baiting, including attacking pro-Israel Democratic members of Congress as ‘Likudniks' and American Jews as ‘Israel Firsters,'" said Block, president and CEO of the Israel Project.

"If the European Union, the U.S. Department of State and more than three dozen countries can uphold a common standard going back to 2005 that says ‘no' to those who single Israel out with slander and boycott and who truck in anti-Zionist, antisemitic rhetoric and discrimination, surely we should expect those seeking the Democratic nomination for President of the United States to do the same," Block said.

Benjamin Weinthal, a research fellow for the Foundation for Defense of Democracies and a correspondent with the Jerusalem Post who is largely responsible for exposing the CAP scandal, told the Free Beacon that Sanders must ensure he is not allowing himself to be steered toward

radical, anti-Semitic elements of the Democratic Party.

"Bernie Sanders in the past has recognized that there are anti-Semitic elements among those promoting BDS," Weinthal said. "I can only hope he will be vigilant and not let his policies be steered in a destructive direction."

Rabbi Abraham Cooper, associate dean of the Simon Wiesenthal Center, was a vocal critic of both Duss and Shakir during their time at CAP. He told the Free Beacon during a Tuesday interview that Sanders's decision to elevate the two staffers to the top of his political organization is "troubling."

"It's clear that when you put these types of people at key positions of your campaign you're sending a signal and the early signal is clearly a troubling one," said Cooper.

"When you have someone who seemed to take a leading role of taking the ACLU from its historic role of standing up for freedom of speech in the United States to becoming a major proponent of anti-Israel moves, of course that's a source of deep concern," Cooper said.

While Cooper expressed optimism that Sanders will make strides to reassure the pro-Israel community, he said that "individuals who are clearly anti-Israel … of course it's a source a concern."

Sanders is no stranger to anti-Israel causes and individuals. He has a penchant for hiring from the far left, anti-Israel ranks.

Simone Zimmerman, a former Sanders top aide who was fired as the senator's Jewish outreach coordinator after profanity-laced screed against Israeli Prime Minister Benjamin Netanyahu came to light, announced late Tuesday that she had accepted a job with B'Tselem, a fringe group primarily known for angling to undermine the elected Israeli government.

Sen. Sanders office did not respond to a request for comment.