Advocates said Johnson made a compelling case for gun control and held his own against LaPierre, a political veteran far more experienced at giving congressional testimony. Ladd Everitt, a spokesman for the Washington-based Coalition to Stop Gun Violence, said Johnson did "a very effective job."

At one point Sen. Dick Durbin, an Illinois Democrat, turned to Johnson and suggested the NRA believes the 2nd Amendment is included in the Constitution to give citizens "the firepower to fight back against you — against our government. So how do you conduct your business in enforcing the law not knowing what is behind that door?"

LaPierre could be heard trying to interject.

"I find it to be scary, creepy and simply just not based on logic," Johnson said.

Johnson was named police chief by then-County Executive Jim Smith in 2007 and became chair of the National Law Enforcement Partnership to Prevent Gun violence last September. The partnership is a coalition of national police leadership groups.

In that role, Johnson has called for extending background checks to all firearm purchases, limiting high-capacity magazines to 10 rounds, banning new semi-automatic assault weapons, and improving the National Instant Criminal Background Check System.

After the Sandy Hook massacre, Johnson appeared with County Executive Kevin Kamenetz at a press conference in Towson to call on state and federal legislators to strengthen gun control laws. Gov. Martin O'Malley renewed calls for tougher state gun laws in his State of the State address on Wednesday.

The county grappled with several gun incidents in schools last year, including a shooting on the first day of school at Perry Hall High in August. In October, the county launched a program to distribute free gun locks to residents, funded by the Baltimore County Police Foundation.

On Tuesday, county officials unveiled a $3.7 million plan that includes the expanded use of cameras in schools and the installation of upgraded electronic entry systems and a new visitor ID system.

But political momentum for action on gun control at the federal level appears to be slipping — partly because of concerns raised by Democratic senators from conservative states. One of the few provisions that does appear to have bipartisan support is stronger background checks of gun buyers.

Licensed firearms dealers must run those checks under federal law, but the requirement doesn't apply to guns bought at gun shows or from private sellers.

Johnson expressed skepticism about another idea some have floated to combat school violence: Arming teachers. He noted the precautions police use to maintain control of their guns and questioned how that would work in a classroom.

"How are you going to safeguard that weapon in a classroom of 16-year-old boys who want to touch it?" he asked.