Maryland Gov. Martin O'Malley (D) details proposed gun-control legislation Jan. 18 at the Maryland State House. (John Wagner/The Washington Post)

Maryland Gov. Martin O’Malley’s ambitious gun-control package would require citizens who move to the state to register guns purchased elsewhere and make it illegal for residents younger than 21 to purchase or own registered firearms or ammunition.

Those restrictions were among new details the governor and his staff released at a news conference Friday as they put the final touches on several gun-control measures that have gained national attention as some of the most aggressive outside of President Obama’s proposals in the wake of last month’s school shootings in Newtown, Conn.

O’Malley (D) will seek a broad assault-weapons ban, new licensing requirements for gun owners and a proposed expansion of reporting mental-health problems to get guns out of the hands of those considered dangerous to others. The details of the governor’s plan were first reported Monday in The Washington Post.

When asked by a reporter, O’Malley said he was also open to discussions with lawmakers about stationing more armed police officers in Maryland public schools — the response, pushed by the National Rifle Association, to public outcry over mass shootings.

Flanked by police chiefs from across the state, O’Malley called his gun-control package his top legislative priority for the 90-day session of the Maryland General Assembly. His agenda also includes getting the state’s death penalty repealed.

On Friday, he released the rest of his legislative proposals. Many had been previously publicized, including expanding early voting and incentives for construction of an offshore wind farm.

The latter measure, which failed in the past two annual sessions, would be financed in part by residential electric customers, whose monthly bills could rise by up to $1.50.

Another proposal would make amend Maryland law to implement the federal Affordable Care Act, including expanding Medicaid.

Lawmakers are also being asked to reauthorize a 2008 law, backed by O’Malley, that allows the collection of DNA samples from people arrested for violent crimes before they have been convicted. The U.S. Supreme Court is examining the constitutionality of the practice.

Absent from O’Malley’s agenda is a transportation funding bill. Aides said he is continuing to mull over whether to introduce a measure similar to a bill last year that would have applied the state sales tax to gasoline purchases, raising more than $600 million a year for road and transit project.

This year’s agenda, meanwhile, attempts to make good on a promise to Prince George’s County lawmakers to change a funding formula that affects how state school aid is distributed. For years, Prince George’s has complained that a calculation based on “net taxable income” does misses late income-tax filers. That, they say, unfairly helps wealthier counties — including Montgomery, where more taxpayers file for extensions — by making them appear less affluent and more in need of state aid.

Changing the formula has been a priority for Prince George’s County Executive Rushern L. Baker III (D), who says the existing terms have cost his county $20 million a year.

O’Malley’s plan, phased in over five years, would provide a more favorable formula for Prince George’s and several other counties but not hurt Montgomery.

Other education-related initiatives in O’Malley’s legislative package include two competitive grant funds. One would provide money to local school districts for “digital learning innovation”; the other would help local school systems and higher-education institutions create early college-access programs.

Also on O’Malley’s agenda: some job-creation initiatives. One seeks to remove barriers to employment that military veterans can face when moving into the civilian workforce. Another provides workforce training collaborations between businesses, local governments and nonprofits groups.