In the third democratic debate for Maryland governor, candidate Anthony Brown explains his role in the launch of the state's health exchange. (Maryland Public Television)

Democratic gubernatorial front-runner Anthony G. Brown said Monday that he should have taken a more direct role in overseeing Maryland’s online health insurance exchange, a project that turned out to be deeply flawed.

Brown, the state’s lieutenant governor, made the remark during a spirited, hour-long debate with his two leading rivals that also included clashes over the candidates’ commitment to expanding pre-kindergarten education in coming years and the tax environment in the state.

Attorney General Douglas F. Gansler was particularly aggressive during the debate, hammering Brown over what he characterized as the mishandling of the health exchange, the most important role given him during his eight years as lieutenant governor.

Brown, who was tasked by Gov. Martin O’Malley (D) with guiding the federal health-care overhaul in the state, said for the first time that he should have insisted on being a member of the board that directly oversaw the rollout of the health exchange, which crashed on its first day and is now being rebuilt using technology from Connecticut.

By playing a more distant policy role, Brown said, he was left in the dark about the extent of the exchange’s problems, which he largely blamed on private contractors. He said he actively tried to fix the flaws as it became clear that users of the Web site were having difficulties signing up for health plans.

“There was nobody more frustrated than me with the troubles that we experienced, and I sincerely regret that any Marylander had difficulties, like many did,” Brown said.

In turn, Brown knocked Gansler for supporting a cut in the corporate income tax rate, which Brown said would limit funds available for expanding pre-kindergarten education programs in coming years — a goal all three Democratic contenders agree on.

“Let’s not give the corporate giveaway,” Brown said. “Let’s give to our 4-year-olds.”

Gansler said that he supports a more gradual pre-K expansion and that Brown had misrepresented his position in a series of “lovely mailers” sent to Democratic voters in recent weeks.

“The lieutenant governor has a very uncomfortable relationship with the truth,” Gansler said.

During the debate, broadcast live statewide from the studios of Maryland Public Television in Owings Mills, Del. Heather R. Mizeur (Montgomery) also weighed in forcefully on both issues.

On the health exchange, she cited her background as a health policy analyst on Capitol Hill, saying, “I’m a governor who will make sure we get this right.”

Mizeur also said she has the most ambitious plan to expand pre-K and close the achievement gap in Maryland schools. The debate also allowed her to tout some of her other more liberal initiatives, including a plan to legalize marijuana.

Brown also said he agreed with Mizeur that a break in Maryland’s estate tax should not have been approved this year by the legislature. Mizeur has said that the measure will benefit wealthy families at the expense of middle-class priorities.

The event, conducted in front of an audience of undecided voters, was the last scheduled televised debate among the Democratic hopefuls before the June 24 primary. Brown, Gansler and Mizeur are scheduled to meet for one final debate, on Baltimore radio station WOLB (1010 AM) on Thursday morning.

All three Democrats participated in a televised debate last month at the University of Maryland, and Gansler and Mizeur met for another debate broadcast on Baltimore television last week that Brown skipped.

The four Republicans vying for their party’s gubernatorial nomination debated earlier Monday in the same studio, vowing to cut taxes and reduce spending. It was a more spirited exchange than the GOP candidates’ previous encounters.

All four Republican hopefuls took aim at tax increases approved during O’Malley’s tenure, which they portrayed as hostile to Maryland businesses.

“My focus is going to be getting the government off our backs and out of our pockets,” said Anne Arundel businessman Larry Hogan, who pledged to roll back as many tax increases from the O’Malley years as possible, after first reducing spending.

Two of his rivals, Harford County Executive David R. Craig and Charles County businessman Charles Lollar, touted plans to eliminate the state’s personal income tax over five years. A fourth candidate, Del. Ronald A. George (Anne Arundel), pledged to grant “emergency” income tax relief of 10 percent to Marylanders by April.

Like the Democratic debate, the hour-long GOP face-off took place in front of a studio audience. But it was recorded and won’t air until Friday at 7 p.m., statewide on Maryland Public Television and on WBAL (Channel 11) in Baltimore.

The GOP candidates agreed that Maryland’s Democratic-led legislature made a mistake by repealing the death penalty in 2013 and said the state should loosen its gun-control laws. But they differed over whether Maryland should move forward with plans to make marijuana available for medical purposes, with Lollar and Craig voicing opposition.

“Marijuana is not the only thing for someone or a family member who’s hurting,” Lollar said.

The most pointed exchange of the hour took place between Hogan and George, over their previous efforts to fight taxes and improve the business climate in Maryland.

Hogan, a Cabinet secretary under the state’s last Republican governor, Robert L. Ehrlich Jr., touted the work he has done since 2011 as leader of the advocacy group Change Maryland, which has criticized the O’Malley administration’s tax increases.

George said that during his years as a member of the House Ways and Means Committee, Hogan’s group had never come to the legislature to testify on tax proposals. And George accused Hogan of using Change Maryland as a promotional vehicle for his own political ambitions. “I think Change Maryland was all about Larry Hogan,” George said.

The role of Hogan’s group has become a sore point within the Republican field, with George and Craig filing a complaint with the state Board of Elections last month accusing the entity of campaign finance violations.

Jenna Johnson contributed to this report.