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

In the wake of the elementary school shooting in Newtown, Conn., Maryland Gov. Martin O’Malley was quick to propose a package of gun-control legislation that would ban assault weapons and create some of the nation’s strictest gun-licensing requirements.

But now his proposal is caught in a tug of war between members of his own party that some fear could threaten its chances of passage.

Liberal Democrats, intent on capitalizing on public support for gun safety after the massacre, have introduced more than dozen pieces of legislation that add several additional gun-control measures.

Some more conservative — and powerful — Democrats, meanwhile, say O’Malley’s plan goes too far, and they are working to carve it up into pieces that might make the licensing portion more difficult to pass.

The challenge mirrors one of the growing problems President Obama faces in Washington: Gun-control advocates have largely painted Republicans as the obstacle to stricter laws, but part of the problem rests with the divergent views of Democrats.

Obama is scheduled to travel to Annapolis on Wednesday to huddle at a retreat with with U.S. Senate Democrats. He is expected to spend part of that time urging the chamber’s majority to stiffen its resolve on guns, including the president’s proposed assault-weapon ban, which has received a lukewarm reception from Senate Majority Leader Harry M. Reid (D-Nev.).

About a mile away, O’Malley on Wednesday is scheduled to testify for the first time on his gun-control plan, which could offer a glimpse of the difficulties both men will probably face persuading members of their own party to toe the line.

O’Malley’s legislation would make Maryland the first state south of the Mason-Dixon line to require gun buyers to submit to digital fingerprinting to obtain a license to purchase a firearm. Researchers in the handful of states that now have similar requirements have tied them to a reduction in so-called straw purchases, which is when someone buys a gun on behalf of another who would not qualify to do so.

“I think there’s a concern that the spirit of Newtown — that resolve — is already beginning to slip away,” said Sen. Jamie B. Raskin (D-Montgomery). “The time to act is now.”

Raskin is among the cadre of Democrats urging members of his party in the Maryland General Assembly to consider O’Malley’s proposal as a starting point to be innovative and to rethink gun control as much as the Constitution will allow. One bill would require gun buyers to obtain insurance on firearms to cover accidental discharge. Another would require gun owners to report a lost or stolen firearm to police within 24 hours.

The insurance mandate would be similar to that required to drive a car, Raskin said. It would be designed in part to bring market forces to bear on gun ownership. Actuaries and insurance adjusters would eventually build a model of who is a safe gun owner, and the price of insurance would follow.

Even without such innovations, Senate President Thomas V. Mike Miller Jr. said in an interview that he thinks O’Malley’s 39-page gun-control bill will probably need to be split into two parts in his chamber to give lawmakers a chance to vote separately on the new licensing requirement.

“I think a lot of lawmakers want an up-or-down vote on something that a lot of people see as the first step toward confiscation” of firearms, said Miller (D-Calvert), holding fast on a line he drew last month when he warned that O’Malley’s licensing requirement could “trample on” Second Amendment rights.

In the House of Delegates, Speaker Michael E. Busch (D-Anne Arundel) has said he will work vigorously to pass the governor’s bill, and he has co-assigned the measure to two committees — limiting the power of Del. Joseph F. Vallario Jr., a Prince George’s County lawmaker who chairs the judiciary committee, where far more gun bills have died than been passed under his tenure.

For his part, O’Malley has remained optimistic that his package will pass.

His licensing plan would require Maryland residents who wish to buy a gun to submit to the fingerprinting, as well as to complete an eight-hour gun safety course and to pass a slightly more restrictive background check than exists now. Maryland State Police would issue the licenses and would be bound to issue the licenses if applicants pass a predetermined list of requirements.

In New York, New Jersey and Massachusetts, police have additional discretion to reject applicants. The license would cost $100, and a subsequent background check would still be required at the time of purchase.

The license would be valid for five years, after which time a resident would need to renew it, or if it lapses, reapply to buy another firearm.