The secretary of the state health department responded Tuesday to a Democratic congressman's request for an analysis of the pros and cons of switching to the federal insurance exchange, arguing in a letter that the risk of switching before the current enrollment period ends outweighs the potential benefits.

In a letter to Rep. John Delaney, a Potomac Democrat, Dr. Joshua M. Sharfstein wrote that in order to rely on the federal insurance exchange, the state would need to develop systems that allow federal enrollment data to interface with the state's Medicaid system. And, he argued, a new site could present a challenge for state residents who have already started an application on the state's exchange.

"The governor recently announced that Maryland does not intend to partner with the federal facilitated marketplace during the current open enrollment period, which ends March 31," Sharfstein wrote. "The governor made this decision because the risks of such a partnership, including the risks of a transition at this time, outweigh the potential benefits."

Delaney has been pressing Gov. Martin O'Malley's administration on adopting the federal health exchange. Despite its own bugs, Delaney has argued, the federal site is singing up new insurance enrollees faster than the state's exchange.

In his letter, Sharfstein pointed to comments from the president of the Maryland-based CareFirst BlueCross BlueShield, Chet Burrell, who urged the state to fix its own site rather than moving to the federal exchange.

Delaney described the state's response as "a one-page letter that, disappointingly...did not contain much significant new information, other than to point out that the state is relying heavily on the advice of the CEO of CareFirst."

Exchanges were created as part of the 2010 Affordable Care Act to allow people who do not buy coverage through their employer to pool risk and purchase private insurance plans online. Maryland was one of 14 states that decided to build its own website rather than rely on the federal government.