EXPLAINER: How states are seeking to loosen controls on guns

Mass shootings in Georgia and Colorado that left at least 18 people dead since last week are reigniting calls from gun control advocates for tighter restrictions on buying firearms and ammunition. But with Democrats in control of the federal government, gun rights advocates have been persuading Republican-run state legislatures to go the other way, making it easier to obtain and carry guns.

How are the politics of gun legislation playing out in the United States this year? Here's the breakdown.

PROSPECTS MIXED FOR LEGISLATION

This month, the Democrat-controlled U.S. House of Representatives adopted measures to expand background checks to all gun purchases and expand the time to to vet people flagged in a nationwide background check system.

But to pass in the Senate, the support of every Democrat would be needed. And that's not a sure thing.

States led by Democrats are pushing to expand some gun control laws.

Maryland lawmakers overrode a veto from Republican Gov. Larry Hogan on a bill that requires background checks for all sales and transfers of rifles and shotguns. Previously, the checks were required only for sales of handguns and long guns by licensed firearms dealers.

In Washington state, a ban on high-capacity magazines has stalled, but a measure to ban carrying weapons openly at the state Capitol or during permitted demonstrations has cleared one house of the Legislature and is awaiting a vote in the other.

California lawmakers are expected to require individual identifiers on all bullet casings to include weapons used by law enforcement. Proponents say the pending legislation is another attempt to help investigate shootings by police as well as make it easier to solve crimes. Critics say it's based on unworkable technology.

At least five states also have...