It's been approximately six months since Representative Debbie Wasserman-Schultz (D-FL) resigned in disgrace from her position as Chair of the Democratic National Committee (DNC).

With a bevy of endorsements from the likes of Elizabeth Warren (D-MA), Bernie Sanders (I-VT), and Chuck Schumer (D-NY), Rep. Keith Ellison (D-MN), the first Muslim elected to the House of Representatives, is considered the front-runner to replace Wasserman-Schultz at the DNC.

Ellison, however, has a problematic background--to borrow progressive parlance.

While Ellison attended the University of Minnesota, he was an outspoken defender of Louis Farrakhan, Nation of Islam leader, and vocal anti-Semite. According to Mother Jones:

Ellison, who had taken to calling himself 'Keith Hakim,' published a series of op-eds in the student paper, the Minnesota Daily, defending the Nation of Islam leader. The center also invited Kwame Ture, the black-power activist formerly known as Stokely Carmichael, to give a speech, during which he called Zionism a form of white supremacy. Ellison, then a member of the Black Law Student Association, introduced him.

Despite Ellison claiming he was never a member of the Nation of Islam, and that he began to realize the error of following Farrakhan in 1995, Mother Jones reports that "[Ellison's] break from Farrakhan was not quite as clean as he portrayed it."

Under the byline Keith X Ellison, months after the march that he described as an epiphany, he penned an op-ed in the Twin Cities black weekly Insight News, pushing back against charges of anti-Semitism directed at Farrakhan. In 1997, nearly two years later, he endorsed a statement again defending Farrakhan.

When Ellison ran (unsuccessfully) for state representative in 1998, Insight News described him as affiliated with the Nation of Islam. Two organizers who worked with him at the time told me they believed Ellison had been a member of the Nation. At community meetings, he was even known to show up in a bow tie, accompanied by dark-suited members of the Fruit of Islam, the Nation's security wing.

It wasn't until 2006 that Ellison fully denounced Farrakhan, and the Nation of Islam leader's anti-Semitism.

However, at a 2010 fundraiser, Ellison gave a speech filled with anti-Israel sentiment, and anti-Semitic undertones:

"The United States foreign policy in the Middle East is governed by what is good or bad through a country of 7 million people...A region of 350 million all turns on a country of 7 million. Does that make sense? Is that logic? Right? When the Americans who trace their roots back to those 350 million get involved, everything changes. Can I say that again?"

The Anti-Defamation League issued a statement regarding Ellison's speech that reads in part:

"...whether intentional or not, his words raise the specter of age-old stereotypes about Jewish control of our government, a poisonous myth that may persist in parts of the world where intolerance thrives, but that has no place in open societies like the U.S."

Now that he's running for DNC Chair, his past is coming back to bite him. In a peculiar twist of events, Ellison just received an endorsement from white supremacist, David Duke:

Duke's somewhat facetious endorsement underscores something troubling. David Duke sees Keith Ellison as someone who understands his worldview. The tweet most likely refers to Ellison's alleged anti-Semitism.

Perhaps more interesting is the lack of response to Duke's tweet from Ellison, or other high-profile Democrats. When Duke endorsed Donald Trump, and Trump refused to immediately condemn the endorsement on CNN, he was rightly excoriated. The calls to denounce Duke were fervent.

Ellison himself tweeted about David Duke's affinity for Donald Trump last July:

Where are the calls for Keith Ellison to denounce David Duke's endorsement? Why isn't Duke's endorsement trending on social media, or being featured on CNN? Why hasn't Ellison denounced Duke on Twitter?

Multiple calls to Ellison's DNC campaign office went unanswered.