Va. Democrats have passed most of their gun-control bills. A big one is still missing.

Both chambers of the Virginia General Assembly have passed major gun-control bills creating universal background checks, a red-flag law and reinstating the former one-handgun-a-month rule.

But a big piece of the Democratic gun-control agenda still hasn’t left the starting gate.

Legislation to ban assault weapons was withdrawn immediately in the Senate and a bill filed in the House of Delegates hasn’t been brought up for a committee hearing.

“The mechanics are still being worked on,” said Jake Rubenstein, a spokesman for House Speaker Eileen Filler-Corn, D-Fairfax.

Several Democrats have acknowledged the complexity of the assault weapon proposal, which raises tough policy questions about how to define what an assault weapon is and what to do about the untold number of AR-15-style rifles and other semi-automatic weapons that might be covered that Virginians already own.

The only proposal currently pending in the legislature, filed by Del. Mark Levine, D-Alexandria, includes a 10-round magazine cap, but would also ban rifles with telescoping stocks, pistol grips, bayonet mounts, flash suppressors and silencers. Levine’s bill lets people who already have those types of weapons keep them, but only if they’re registered with the state for a fee of up to $50.

Levine said Thursday he’s actively working with the governor and others to find common ground.

“I’m working with all parties, including critics, to provide the best possible vehicle to decrease mass acts of violence while at the same time protecting legitimate uses like hunting, sport shooting and self defense,” Levine said.

Stopping the assault weapon bills — the only proposals that would significantly restrict what types of guns Virginians can buy and own  — has been a top priority for the National Rifle Association and other pro-gun groups. The idea of banning weapons Virginians already have fueled a pro-gun backlash that led thousands of gun-control opponents to rally at the Capitol earlier this month.

Republicans said the delay addressing the legislation likely reflects the controversy surrounding the proposal.

“That’s the legislation that primarily prompted the Second Amendment sanctuary movement across the commonwealth,” said House Minority Leader Todd Gilbert, R-Shenandoah.

Most Republicans have voted against all the gun-control bills, but the Democratic majorities don’t appear to have had any major trouble getting their members behind the legislation.

On Thursday, the House of Delegates approved seven of the eight gun-control proposals championed by Gov. Ralph Northam, including bills to require background checks for all gun sales and transfers, a red flag law allowing courts to issue substantial risk protection orders to temporarily seize guns from people deemed a threat to themselves or others and reinstating the one-handgun-a-month law. Similar bills have already passed the Senate, so the two chambers must now reconcile any differences before sending the legislation to the governor for final approval.

The House also passed bills to require gun owners to report lost or stolen firearms within 24 hours, bar people subject to domestic violence protective orders from possessing guns and strengthen criminal penalties for anyone who recklessly leaves guns around children and teenagers under 18.

The Senate has not yet taken up bills dealing with gun access by minors or reporting rules for lost guns.

One big difference between the House and Senate gun bills is how far each chamber is willing to go to empower local governments to set their own gun rules.

Under current law, localities have little to no power to pass ordinances dealing with guns.

The Senate passed a bill that would let localities ban guns in public buildings, parks and at permitted events like political rallies, festivals and farmers markets.

The House approved a far broader bill on local gun-control that would allow cities, counties and towns to adopt their own gun laws, including rules on what types of guns are legal within their jurisdiction.

Republicans have called that proposal unworkable, saying it would lead to patchwork of gun regulations that would make it impossible for traveling gun owners to know if they were following the law as they pass from locality to locality.

“You could be legally carrying in one jurisdiction and then cross a line and be a criminal,” said Del. Nick Rush, R-Montgomery.

Del. Marcia Price, D-Newport News, the bill’s patron, said it would give cities that suffer from gun violence more power to keep their residents safe.

“It is a gun owner’s responsibility to know the laws and ordinances of where they live and where they plan to travel,” Price said. “This would be no different.”

Each chamber has to finish voting on its own bills by Feb. 11.