A White House spokesman couldn't say Tuesday whether or not President Barack Obama's personal views on medical marijuana had changed after a column and documentary written by CNN Chief Medical Correspondent Dr. Sanjay Gupta detailing his own shift on the issue went viral.

Deputy Press Secretary Josh Earnest, asked if the White House had any official reaction to the column and if the president "has been personally looking at that issue," said he hadn't read it. "I have to confess I did not see the Sanjay Gupta column that you're referring to, so it's hard for me to comment on it at this point," Earnest said.

The online essay, published August 9, was titled "Why I changed my mind on weed." In it, Gupta described changing his own stance on medical marijuana after researching the topic for his CNN documentary "Weed."

He also apologized for what he said was his misguided previous stance.

"I apologize because I didn't look hard enough, until now," Gupta wrote. "I didn't look far enough. I didn't review papers from smaller labs in other countries doing some remarkable research, and I was too dismissive of the loud chorus of legitimate patients whose symptoms improved on cannabis."

"We have been terribly and systematically misled for nearly 70 years in the United States, and I apologize for my own role in that," he added later.

The column received millions of page views online and was covered heavily by a range of media outlets. Gupta was a candidate for surgeon general in 2009, but later told CNN's Larry King he withdrew his name from consideration so he could maintain his surgical career and continue spending time with his family.

Obama last weighed in on the use of marijuana after two states -- Washington and Colorado -- legalized the recreational use of the drug.

"This is a tough problem, because Congress has not yet changed the law," Obama said. "I head up the executive branch; we're supposed to be carrying out laws. And so what we're going to need to have is a conversation about, How do you reconcile a federal law that still says marijuana is a federal offense and state laws that say that it's legal?"

Supporters of medical marijuana have largely been disappointed in the Obama administration's record on the issue. While many were hopeful Obama would discontinue Bush-era crackdowns on dispensaries in states allowing the medical use of cannabis, those raids have ramped up since 2011. Users of medical marijuana, however, have mostly been left alone by the federal government.

Marijuana is listed as a Schedule I drug by the Drug Enforcement Agency, meaning it's considered dangerous and has no medical use. Other Schedule I drugs include heroin, ecstasy, and psychedelic mushrooms. Medical marijuana advocates say it should be listed under Schedule II, comparing it to other prescription painkillers that have a high potential for abuse.

CNN's Kevin Liptake contributed to this report