(CNN) - House Judiciary Committee Chairman Rep. John Conyers wrote a letter to fellow representative Thursday saying the selection of CNN medical correspondent Sanjay Gupta is “not in the best interests of the nation.”

“It is not in the best interests of the nation to have someone like this who lacks the requisite experience needed to oversee the federal agency that provides crucial health care assistance to some of the poorest and most underserved communities in America,” he wrote.

A Democratic aide close to Conyers says he opposes Gupta for surgeon general because the Michigan Democrat "is a strong advocate for single-payer healthcare, and is unconvinced that Gupta will advocate for the type or reform that he believes is needed."

Conyers does not serve on any committees with jurisdiction over healthcare, but has pushed for a single-payer system for years, introducing the same bill every Congress.

Gupta and the Obama transition have not commented publicly on the letter. None of the senators who would be voting to confirm Gupta have spoken critically of him.

When President-elect Obama recently solicited people to write into change.gov and give suggestions for new approaches in the healthcare system, Conyers appealed to grassroots organizations he's worked with on the issue to write in and tell the administration to consider the single-payer system.

Gupta, a former White House fellow and a special adviser to then-first lady Hillary Clinton, has been approached by the Obama administration about the U.S. surgeon general's post, according to sources at the transition and within CNN. Gupta, a neurosurgeon, has declined comment on the matter.