On the same day that he unveiled an urban agenda that highlights public transportation, affordable housing, and criminal justice reform, Michigan gubernatorial candidate Abdul El-Sayed came under fire in what he has described as a “birther”-like campaign questioning his eligibility to run for governor.

El-Sayed, a lifelong Michigander whose campaign has raised nearly $2 million, could be the first Muslim-American governor in the United States. He is considered the most serious challenger to Democratic frontrunner Gretchen Whitmer ahead of the August primary. And on Monday, Bridge, a Michigan magazine, published an article saying the stint El-Sayed spent as a medical student and professor at Columbia University in New York between 2013 and 2016 could be used against him, writing that “questions surrounding El-Sayed’s candidacy are an open secret among Democrats, particularly in southeast Michigan.”

Most of the Democrats and election lawyers the magazine interviewed spoke on condition of anonymity, because they “didn’t want to be caught up in a controversy.” A controversy has resulted nonetheless, with much of the Detroit press picking up the story. El-Sayed, in a fundraising email, said the article is the work of “establishment Democrats resorting to the kind of birther tactics that opponents to Barack Obama used to discredit his run for the presidency.”

Asked about the dispute, Whitmer’s campaign neither condemned nor supported the allegations against El-Sayed and had nothing to say about his response.

“Whitmer is not focused on chatter about who is or is not getting into the race and frankly there has been way too much distraction from how we fix our roads, grow our economy, and protect health care for Michigan families,” Annie Ellison, a spokesperson for the campaign, told The Intercept. “Anything that distracts from how we solve problems and put people first in this state is not something she’s paying attention to.”

The Michigan constitution provides that a candidate for governor must have been a “registered elector in this state” for four years prior to the election. El-Sayed grew up in metro Detroit. He played high school sports and started medical school at the University of Michigan. He completed his medical education in New York, but returned to Detroit in 2015 after being tapped to lead the Detroit Health Department. “While we knew the attacks were coming, we didn’t think they would come in the form of insider Democrats using Trump’s ‘birther’ tactics,” the campaign said in a statement.

The lawyers and Democratic officials interviewed by Bridge say that his time in New York — and the fact that he has a driver’s license in that state — means he does not meet the basic qualifications for office.

One Democratic elected official told the magazine, “There will be a court case, guaranteed. The only question is who is going to step up to take him out.” Another framed his questions about El-Sayed’s eligibility in the context of concern for the Democratic party. “One party leader said he fears a ‘nightmare scenario’ in which El-Sayed comes from behind and wins the Democratic Party primary in August, then is knocked off the November general election ballot through a lawsuit brought by Republicans,” the article says.

When he lived in New York, El-Sayed obtained a local driver’s license in 2013, which meant he had to discard his Michigan license. But the Detroit Free Press queried the secretary of state and was told that while it’s accurate that El-Sayed didn’t vote in the state of Michigan between 2013 and 2016, he didn’t lose his voter registration.

Fred Woodhams, a communications officer in the secretary of state’s office, offered similar comments to us and added that the office cannot make a final ruling until El-Sayed officially files paperwork on April 24.

“I can confirm that, according to the state’s voter records, El-Sayed has been continuously registered to vote since 2003. El-Sayed has not filed to run for governor so we have no further comment. Candidates have until April 24 to file,” Woodhams said in an email.

El-Sayed’s three years in New York did cause his voter registration to be placed on “cancellation countdown status,” but because he voted in November 2016 in Michigan, his status was returned to normal. He also owned a residence in Ann Arbor even while living in New York.

James Allen, a lawyer working with El-Sayed’s campaign, disputed the challenge to the candidate’s legacy in a statement to The Intercept.

The bottom line is this: Abdul is a qualified elector and is thus eligible to run for Governor because he is and has continuously been a resident and registered voter. There is always a danger when people try to make a legal claim without knowing all the facts. It’s like trying to make a diagnosis without ever seeing the patient. Abdul consistently and continuously maintained his connection to the state of Michigan as a registered voter and maintaining legal residency in the state between 2011-2015 (i.e. in the years required by law for him to be a qualified elector).

Robert Lenhard, a former chair of the Federal Election Commission who is serving as outside counsel to the El-Sayed campaign, issued a similar statement.

We have looked at this question closely and are confident Abdul El-Sayed is qualified to run for Governor of Michigan. He is a lifelong resident of Michigan. He was born here, went to school here, and married here. He has been a property owner, a taxpayer, a registered voter and a resident of Michigan throughout the qualifying period under State law. Michigan law has never held that absences from the state for school or work cause you to lose your residence. This issue is just a red herring.

Polls have shown Whitmer with a double-digit lead over the other Democrats in the race, and she has raised about $1 million more than El-Sayed has. (A December poll showed Republican Bill Schuette with a 3-point lead over Whitmer for the general election.) Still, El-Sayed’s campaign has garnered a wave of national media attention and his progressive politics have earned him the support of veterans of the 2016 Bernie Sanders presidential campaign. He is the 33-year-old son of an Egyptian immigrant, and he has drawn comparisons to Obama, owing in part to his youth and charismatic presence on the stump. (El-Sayed is, in fact, highly critical of the former president.)

The partisan primaries will take place on August 7.