One of Maryland’s two leading gubernatorial candidates, Republican nominee Larry Hogan attacks his Democratic opponent, Anthony G. Brown. This ad is paid for by Hogan-Rutherford Committee to change Maryland. (You Tube: Larry Hogan)

As the race for Maryland governor continues, Lt. Gov. Anthony G. Brown (D) is once again having to defend his role — or lack of one — in the launch of the state’s online health insurance marketplace, which crashed on its first day and is now being rebuilt.

Larry Hogan, Brown’s Republican rival, released a television ad Friday that declares Brown “just not ready to be governor” because of the problems the state faced in fully implementing the Affordable Care Act in Maryland. The 30-second ad, which will air in Baltimore, is titled “Weak Leadership.”

It’s the same line of attack that Maryland Attorney General Douglas F. Gansler used when he faced Brown in the Democratic primary this spring. But the issue did not seem to stick to Brown, who has said that he had no day-to-day responsibility for the launch of the Web site and was not informed of potential problems. Brown won the Democratic primary with more than half of votes.

The Hogan campaign’s new ad opens with video footage of Brown introducing himself and saying: “I’m proud that Governor O’Malley has asked me to lead the O’Malley-Brown administration’s efforts in health care.” The ad then shows news clips that quote Democrats and others criticizing the rollout of the health exchange, including Rep. Chris Van Hollen (D-Md.) saying: “Maryland’s a mess. There’s no doubt about it.”

Van Hollen’s comment came during a December 2013 appearance on “Meet the Press,” during which he defended the Obama administration’s problems launching and pointed out that other states have also had problems, including Maryland.

Brown’s campaign declined to comment on the ad. Instead, a campaign spokesman passed along a statement from Van Hollen that echoed language frequently used by the campaign, including calling Hogan a “conservative Republican” with a “conservative agenda.”

“No one was satisfied with the launch, but the Lt. Governor rolled up his sleeves and led the state effort to ensure over 400,000 Marylanders had access to quality affordable health care,” Van Hollen said in the statement, which was confirmed by a spokeswoman in his Congressional office. “Nothing the Republicans say will change that.”

Soon after Hogan’s team released the ad Friday, he and Brown both spoke to an audience of Maryland mayors and other municipal leaders in Annapolis. The candidates did not appear on the stage together, did not answer questions from the audience and did not share any previously unknown information about their visions for the state.