Senate Majority Leader Mitch McConnell is demanding answers from the Obama administration about the cost of a proposed campaign geared towards promoting healthcare exchanges created under the Affordable Care Act.

"I am interested in knowing what resources the administration believes it has for such a campaign," McConnell wrote in a Friday letter to Health and Human Services Secretary Sylvia Burwell.

McConnell said he only learned of the exchanges by reading reports in the media, and took a shot at "the failed Obamacare exchanges" by noting that major insurers are starting to pull out.

"Nearly every day brings another set of stories about the dysfunction of the Obamacare exchanges and the negative impact on consumers," he wrote. "More recently, we have learned ... that Obamacare's onerous rules and poor implementation have caused a number of insurers to withdraw their participation from the exchanges, leading to fewer choices ... for consumers in the marketplace."

He also questioned why the administration wasn't instead directing funds to stop the spread of Zika in the United States.

McConnell demanded answers from Burwell about how much federal funding had already been appropriated for the Obamacare public relations campaign, and whether the administration believed that money was included in the budget for the 2016 or 2017 fiscal years.

"Advertising is helpful when you have a good product to sell that people don't fully understand," McConnell wrote. "Obamacare's problem isn't that it is poorly understood, but rather that people understand all too well that the law costs too much and it isn't working like the administration promised."