The likely nominee to be the next Housing and Urban Development secretary could face scrutiny about how he made his money and how qualified he is for a cabinet-level position.

How does San Antonio Mayor Julian Castro make his money?

In a Feb. 5, 2013 file photo, San Antonio, Texas Mayor Julian Castro, right, testifies on Capitol Hill in Washington before the House Judiciary Committee. President Barack Obama’s expected nomination of Castro as secretary of Housing and Urban Development could test the 39-year-old’s ability to navigate Washington ahead of 2016 elections, Texas Democrats say. (AP Photo/Susan Walsh, File)

San Antonio Mayor Julian Castro is reportedly on the verge of being tapped to lead HUD when current Secretary Sean Donovan becomes the director of the Office of Management and Budget.

But Castro – a rising star in the Democratic party – has been a part-time mayor without executive authority, and has already come under political fire for raking in money for legal referrals.

Reports surfaced over the weekend about the pending changes, but White House press secretary Jay Carney declined to talk about any personnel changes.

“You probably remember that President Obama asked Mayor Castro to deliver the keynote address at the president’s convention in 2012,” Carney said, referring to the 2012 Democratic National Convention in Charlotte. “I think that reflects the high regard in which President Obama holds Mayor Castro. He’s mayor of a significantly sized city and has done an excellent job in that position.”

San Antonio, the seventh largest city in the United States, has a council-manager and weak mayoral form of government, which means the mayor is essentially another member of the city council, whereas the city manager – in this case Sheryl Sculley – is the executive.

“The Office of the City Manager serves as the focal point for the executive leadership and direction of the city organization,” the city’s website says. “The office works closely with the Mayor and City Council to ensure that City programs and operations reflect policy goals and objectives established by the City Council.”

Sculley earns a $355,000 salary, the Washington Examiner reported. Castro on the other hand is paid $20 per council meeting and one time $2,000 payment.

“So I basically make $4,000 a year,” Castro told KENS.

So how does he earn a living? It’s a point the Examiner raised, and the San Antonio News-Express has followed since 2009, the year Castro was elected, when his local newspaper raised the issue of the money he made from a legal referral.

The issue regarded a case in which a plaintiff retained Castro. Castro referred the client to the much larger law firm of major Democratic donor Mikal Watts. Watts contributed more than $246,000 to Democratic candidates since 1992, including maxing out at $2,300 to Obama’s 2008 presidential campaign, according to the Center for Responsive Politics, which tracks money in politics. After Watts won the case, Castro received a seven figure referral fee, the News-Express reported on March 22, 2009.

Because Castro is a rising star who has even been mentioned as a potential Democratic vice presidential candidate for 2016, some of those questions will likely emerge in a Senate confirmation hearing.

Since delivering the 2012 keynote speech at the Democratic National Convention, Castro has ben able to cash in on public speaking gigs, as well as a book deal, the News-Express recently reported. Castro earned more than $200,000 in 2013. Most of that came from a $127,500 advance for a memoir the 39-year-old is writing. The rest came mostly from being paid $8,500 to $16,250 per speech.