Lt. Gov. Anthony Brown, center, talks about problems with Maryland’s health care exchange on Tuesday in Baltimore. Joshua Sharfstein, Maryland’s health secretary, stands to the right, and Carolyn Quattrocki, the interim director of the exchange, is on left. (Brian Witte/Associated Press)

Lt. Gov. Anthony G. Brown said Tuesday that “much, much work” still needs to be done on Maryland’s online health insurance exchange and declined to say whether the state will meet a mid-December target set by Gov. Martin O’Malley to fix the major glitches.

Brown’s assessment came at a half-hour news conference just days after the exchange’s executive director resigned and a leading Democratic rival for governor accused Brown of ducking responsibility on the project, which has been plagued by technological problems.

Brown (D), who has taken a leadership role in implementing the federal health-care law, cited some progress, including a “surge” in staff assigned to the exchange and a “significant” increase last week in the number of people who were able to navigate the Web site and enroll in private insurance plans.

“Every day we get better at identifying the problems,” said Brown. “My focus is on resolving the issues and ensuring that every Marylander can obtain quality, affordable health care.”

Asked during his news conference in Baltimore whether he thinks the state will meet the deadline set by O’Malley (D) to fix the site’s major glitches, Brown did not answer directly.

“The governor and I will certainly report back on the status of that timeline that he laid out,” Brown said. “Certainly there will be a timely update on that timeline, that mid-December timeline that was articulated.”

O’Malley announced the mid-December goal at a news conference two weeks ago as Brown sat by his side. The governor, who was wrapping up a nine-day trade mission to Brazil and El Salvador, was not present Tuesday.

The problems with the site have become a growing political liability for the lieutenant governor in his bid to succeed O’Malley, who is term-limited and must step down in January 2015. Attorney General Douglas F. Gansler, Brown’s chief rival in the June Democratic primary, has been hammering Brown almost daily on the issue.

“Accountability seems not to be a priority for the lieutenant governor,” Gansler spokesman Bob Wheelock said Tuesday after Brown’s news conference. “People are not getting answers to the questions they deserve.”

Brown also has caught flak from frustrated lawmakers in both parties.

“We’d like to hear somebody assume ownership of the debacle so it can move forward,” Senate Minority Leader David R. Brinkley (R-Frederick) said.

“Ultimately, it rests with O’Malley, but Brown was the colonel put in charge of it, and if he’s hoping to take over the leadership of the state, he should accept responsibility,” he said.

Brown does not directly oversee the day-to-day operations of the health-care exchange, which lawmakers set up as independent agency. But along with O’Malley’s health secretary, Brown co-chairs the council that has been overseeing health-care reforms in the state.

As of Tuesday, Brown said, about 5,200 people had chosen to sign up for private health plans through Maryland’s exchange. Maryland’s performance has lagged some of the other states that chose to run their own insurance marketplaces rather than rely on the Web site run by the federal government.

The number who enrolled in Maryland during the past week was double that of any other week since the launch of the exchange on Oct. 1, Brown said. Still, the state remains a long way from its goal of enrolling 150,000 uninsured Marylanders by the end of March.

Brown hedged when asked whether that remains a realistic target.

“Our hope was to get to 150,000 certainly within the first year,” he said. “That continues to be our focus.”

Brown said Tuesday that he received no advance warning from Rebecca Pearce, who resigned Friday as director the exchange, or from other officials that Maryland would face the kind of problems it did when the exchange went live on Oct. 1.

“Part of leadership is delegating responsibility,” Brown said in an interview. “There are 50,000 employees that work for state government. There’s a delegation of management and responsibility, and you rely on accurate reporting throughout the organization. On Oct. 1, it became very clear that the reports were not accurate.”