By Mark Felsenthal

WASHINGTON (Reuters) - Vice President Joe Biden took the Obama administration's case for gun control to the gun-friendly state of Virginia on Friday, part of a White House strategy to urge the public to pressure Congress into passing laws aimed at curbing firearms violence.

"We're going to continue to go around the country," Biden said after a roundtable talk with officials and experts on gun violence at Virginia Commonwealth University in Richmond. "We're going to be doing a lot of more of this, and with the help of our colleagues in the House (of Representatives) and the Senate we're going to get something done."

The event reflected how Biden continues to serve as the administration's key player in the gun-control debate. The issue soared to the top of Obama's priority list after 20 children and six adults were killed on December 14 by a gunman at a school in Newtown, Connecticut.

It also offered a hint of the administration's strategy as it pursues the most significant U.S. gun-control steps in decades. Obama wants to revive a U.S. ban on military-style assault weapons, a proposal that faces a tough battle in Congress, and put in place mandatory background checks for all gun buyers, a step viewed as having a better chance of success.

Virginia is home to the headquarters of the National Rifle Association, the nation's largest gun-rights group and the loudest critic of the Democratic president's plan.

Virginia is a politically divided state that Obama won in both of his runs for the presidency. It also is home to Virginia Tech University in Blacksburg, where in 2007 a gunman killed 32 people and wounded 17 others.

Many Democrats see Virginia, with its rural history of gun ownership and its booming suburbs where Obama and Democrats have done well in recent years, as an example of warming attitudes toward gun restrictions in many communities nationwide.

Friday's roundtable was another indication that Obama is willing to use considerable resources to push gun-control proposals. Biden was joined by Homeland Security Secretary Janet Napolitano and Health and Human Services Secretary Kathleen Sebelius, along with several Virginia lawmakers.

'BOUND AND DETERMINED'

In New York, U.S. Attorney General Eric Holder gave a forceful defense of Obama's gun control efforts. "We are bound and determined to do this," he said in a speech to the New York State district attorneys association. "This is not a time for complacency."

Holder also defended Obama's use of executive orders to take certain steps without congressional approval. "All of the president's actions have been consistent with the historical use of executive power - and none will impinge on the Second Amendment rights of responsible, law-abiding citizens and gun owners," Holder said, referring to the constitutional right to bear arms.

One expert said Obama is working to keep the issue in the public consciousness. "It would seem to be a clear effort to continue to stoke public attention so it doesn't go away as it has in the past," said Robert Spitzer, a professor of political science at the State University of New York at Cortland who has written about the politics of gun control.

"Part of the goal is to try to cultivate some support from the gun-owning community," Spitzer said.

Past efforts to restrict gun ownership have foundered in the face of strong opposition from gun owners, the NRA and other gun-rights groups. Gun ownership rights are enshrined in the U.S. Constitution. The ability of lawmakers to restrict those rights is a persistent source of tension in American politics.

Gun control was not a major priority of Obama's administration before the Newtown shootings.

Since Newtown, pro-gun lawmakers such as West Virginia Senator Joe Manchin, a Democrat, and Iowa Senator Chuck Grassley, a Republican, have indicated willingness to buck pressure from the NRA and consider new restrictions on guns.

Manchin said on Monday he is open to more regulation of military-style rifles like the one used in Newtown. "This awful massacre of our youngest children has changed us, and everything should be on the table," said Manchin, who once ran a campaign ad in which he shot a copy of an environmental bill with a rifle.

A PITCH TO GUN OWNERS

Obama and Biden have suggested they will take several trips to make the case to the public for the administration's plan. Biden has sought to reassure gun owners that the plan would not infringe on gun ownership, even as it would ban assault weapons.

In a video released on Thursday, the vice president said that when it comes to self-protection, a shotgun is better than an assault rifle.

"A shotgun will keep you a lot safer, a double-barreled shotgun, than the assault weapon in somebody's hands who doesn't know how to use it, even one who does know how to use it," Biden said. "It's harder to use an assault weapon and hit something than it is to use a shotgun, OK? If you want to keep people away in an earthquake, buy some shotgun shells."

Obama plans to launch his second-term push for a U.S. immigration overhaul during a visit to Nevada next week, the White House said on Friday. His visit also could offer a chance to make his case for gun control in another state with a tradition of gun ownership.

Joining the White House's efforts will be Organizing for Action, a non-profit group that evolved out of Obama's re-election campaign to build public support for his policy initiatives. Jim Messina, Obama's former campaign manager and the group's leader, has cited efforts to prevent gun violence as one of the issues he plans to address.

(Additional reporting by Joseph Ax in New York; Editing by David Lindsey and Will Dunham)