As legislators grilled Lt. Gov. Anthony G. Brown on Tuesday over the dismal debut of Maryland's health insurance exchange, the O'Malley administration stood by the website and said it will not switch to the federal version.

Rejecting calls to shut down the state's bug-ridden website, Gov. Martin O'Malley's office issued a statement saying the state would keep it running while working to improve it for at least the next 21/2 months. The exchange was created to implement the federal Affordable Care Act and give Marylanders a place to buy health plans or enroll in Medicaid.

"The governor and lieutenant governor have decided that during the remaining months of open enrollment, the risks associated with a transition to the federal site would outweigh the benefits," the statement said.

Open enrollment for insurance under the health care law ends March 31.

State officials could revisit that decision after the end of enrollment, said Dr. Joshua Sharfstein, Maryland health secretary, at a Senate briefing on the exchange's botched rollout. He promised senators that any decision to stick with the state exchange would be based on objective factors, not whether a shift would be politically embarrassing.

Brown, representing the administration at hearings in the House and Senate, came under fire from Republicans.

"This is all malpractice," said Senate Minority Leader David R. Brinkley of Frederick County. "Because the people of Maryland expected something. They didn't get it."

Under pressure from Sen. Allan H. Kittleman, a Howard County Republican, Brown declined to apologize for the failed launch. Brown, a Democratic candidate for governor and the administration's point man on implementing the federal law known as Obamacare, said constituents want progress on insuring more Marylanders, not apologies.

"An apology would amount to very little for those Marylanders who are struggling," he told Kittleman.

When he followed Brown to the witness table, Sharfstein showed no such hesitancy.

"I apologize to the many Marylanders who have struggled with the website and the call center, and I regret the anxiety experienced by individuals and families who are seeking health insurance and who have been frustrated in the efforts to obtain it," Sharfstein said.

"I really wish the lieutenant governor had said the same thing," Kittleman said later.

Brown acknowledged that when many Marylanders attempted to shop for insurance on the website after its Oct. 1 launch, they encountered error messages or blank screens. But he said those problems now occur in less than 1 percent of cases.

"We have fixed that," Brown said.

He said the administration based the decision to stick with the state site in part on advice from insurers, particularly CareFirst BlueCross BlueShield, the state's largest insurer. Company officials warned it would be risky to try to switch systems before the end of open enrollment.

"Their belief was right now you're in better shape staying where you are," Brown said.

The administration had come under pressure from some — notably Democratic U.S. Rep. John Delaney — to switch to the federal website. That site had its own severe problems when it began operations, but the effort to fix it has gone faster than Maryland's attempts to improve its site.

Brown appeared before the committees with jurisdiction over health care in the House and Senate to urge swift passage of emergency legislation that would provide an alternative way for certain consumers — those who tried but failed because of glitches to sign up for insurance last year — to get coverage retroactive to Jan. 1.

The measure would open the Maryland Health Insurance Plan, a high-risk pool that's been in effect since 2003, to those unsuccessful applicants frustrated by the exchange's problems.

The lieutenant governor said the law is needed even though the four companies that offer insurance through the exchange have agreed to make retroactive coverage available to people who tried to sign up last year. He described the emergency bill as a "temporary, last-resort option."