A Senate committee is looking into the millions of taxpayer dollars being spent on ads to promote ObamaCare enrollment.

FoxNews.com has confirmed the Health and Human Services budget for “paid media” is about $35 million for the current enrollment period – focusing on the 38 states using HealthCare.gov.

But Senate Finance Committee Chairman Orrin Hatch, R-Utah, raised concerns that agency ad spending is becoming a “black box” that is difficult to track. Citing a study that also showed the total federal government budget for ads and PR was nearly $1 billion in fiscal 2013, Hatch recently fired off a letter to the acting head of the Centers for Medicare and Medicaid Services (CMS) asking for a full accounting of agency ad spending.

“Increased transparency on government spending on advertising will improve accountability and help ensure that the taxes from hardworking Americans are not squandered and wasted on ineffective or misguided government programs,” he wrote to Acting Administrator Andrew M. Slavitt.

Politico first reported that HHS was spending the $35 million to run ads in English and Spanish to encourage people to sign up. Hatch cited the report in sending the letter to Slavitt.

An HHS spokesman declined to provide details to FoxNews.com beyond confirming that CMS planned to spend $35 million on paid media advertisements. The department is also using email and social media, and is partnering with 30 women’s organizations to target women, but it remains unclear whether those efforts are included in the HHS advertising budget.

The spokesman said in an email that they “have gotten smarter about how we reach people but we need to get even smarter, and the lessons we learn from testing will continue to pay dividends on enrolling the uninsured for years to come.”

Hatch’s committee set a Nov. 25 deadline for information on the spending. The push to promote the health care exchanges comes after HHS estimated 10 million people would enroll in ObamaCare by the end of 2016, a far lower number than the original prediction that enrollment would reach 21 million by the end of 2016. This comes as America’s largest insurer, UnitedHealth Group, suggested Thursday it might consider dropping out of the exchanges in 2017, citing flagging enrollment and high costs.

It is difficult to accurately ascertain how much the federal government spends annually on advertising and messaging campaigns because no government-wide definition of advertising exists, and there is no central authority with oversight responsibility over media contracts.

According to a June 2014 Congressional Research Service (CRS) report, the Obama administration spent a minimum of $4.4 billion on outside advertising contracts between fiscal 2009 and fiscal 2013, a figure that did not include in-house expenditures.

HHS was second only to the Department of Defense, spending $197.4 million on advertising in fiscal 2013, CRS reported.

Hatch’s letter is not the first time ObamaCare promotions have raised concern.

In 2012, reports that HHS was spending $20 million on a campaign to promote ObamaCare drew similar scrutiny and demands for details from Congress.

In 2010, the nonpartisan Government Accountability Office (GAO) reported the Obama administration spent nearly $20 million on a Medicare brochure that contained “instances in which HHS presented abbreviated information and a positive view of Patient Protection and Affordable Care Act (PPACA) that is not universally shared.”

GAO concluded that “nothing in the brochure constitutes communications that are purely partisan, self-aggrandizing, or covert.” 

Another HHS agency has drawn the attention of the Senate Budget Committee after The Washington Post reported the public relations firm Edelman was hired to “refine their agency messaging” with reporters.

“Agency spending on advertising, public relations and media relations is largely a black box,” committee Chairman Mike Enzi, R-Wyo., wrote in an October letter to Office of Management and Budget Director Shaun Donovan seeking details about the firm’s contract with HHS’ Substance Abuse and Mental Health Services Administration (SAMHSA).

In its fiscal 2016 budget, SAMSHA asked for $16 million for “public awareness and support.”

Noting the Obama administration consistently asks for Congress to raise the debt limit, Enzi said any “unnecessary media relations spending is a cost that the nation simply cannot afford.”

A committee spokesman said OMB missed its deadline, but noted they are working to provide the requested materials.