Missouri Gov. Jay Nixon (D). (Reuters)

In Washington in the days after the Orlando massacre, there was a lot of talk about new gun-control measures but very little legislative action.

In the states, it's a different story.

State legislatures are where most of the gun policy fights have been happening for years anyway. And one of the first big gun policy showdowns since Orlando could go down in Missouri.

There, Gov. Jay Nixon (D) vetoed a wide-ranging pro-gun-rights bill Monday that would have allowed residents to carry concealed guns without a permit. It also would have put Missouri among the "stand your ground" states allowing people to use deadly force if they feel their life is threatened. (If this sounds familiar, that law was in the national spotlight after George Zimmerman shot Trayvon Martin in Florida in 2012.)

"I cannot support the extreme step of ... eliminating sensible protections like background checks and training requirements, and taking away the ability of sheriffs to protect their communities," Nixon said in a statement. (Here's his full veto message to lawmakers.)

Nixon's veto sets up a potential face-off with the state's Republican-dominated legislature. According to the Kansas City Star's Jason Hancock, the gun bill passed in the final few minutes of its session by a large-enough majority to override Nixon's veto. In other words, unless Nixon and his party can win some converts who formerly supported the bill, it will likely move forward.

The legislature is out of session until September, but there's good reason to believe that when they return, they'll have little trouble overriding Nixon's veto and little incentive not to. Republicans have a supermajority in both chambers and have used it to override Nixon's vetoes before. And when it comes to guns, an increasingly conservative Missouri has spent the past decade embracing looser laws.

In 2007, lawmakers got rid of a permit requirement for people buying handguns. Then they lowered the age required to get a concealed carry permit to 19 and blocked local governments from limiting where people can openly carry their guns, Hancock said. The Law Center to Prevent Gun Violence, a nonprofit group that supports gun control and tracks state legislation, ranks Missouri among the 10 states with the loosest gun laws.

Then there's the matter of political will and leverage — or lack thereof. Nixon is term-limited, which sets up a heated race for his replacement in a state that has voted for the Republican presidential candidate every election since 2000. And the presumptive Democratic nominee to replace him, state Attorney General Chris Koster, doesn't appear to support the veto. Koster, a former Republican, told the Associated Press in May that he hadn't heard anything during the bill's debate that would make him think a veto was necessary.

Missouri may be the biggest showdown after the Orlando shooting, but as gun control proponents are quick to point out, it's not the only gun legislation moving since the massacre more than two weeks ago.

Here are a few, as tracked by the Law Center to Prevent Gun Violence. Notice they're mostly in blue states that already support gun control:

That last state — New Jersey — is also worth keeping an eye on. Four days after Orlando, Democratic lawmakers announced that they'd try to override an earlier veto on a gun control bill by Gov. Chris Christie (R).

Christie vetoed the bipartisan bill, which required anyone convicted of domestic violence to surrender their guns, in May. NJ.com's Claude Brodesser said lawmakers decided after Orlando to fight him on it.

"If that doesn't send a signal that we need to do more to protect our citizens, I don't know what does," state Senate President Steve Sweeney (D) said at the time. Orlando shooter Omar Mateen's ex-wife has said Mateen abused her.

In contrast to what we see in Missouri, it's less clear that lawmakers in New Jersey have the numbers to override a Christie veto. But state legislatures and governor's mansions remain the places to watch to see whether there will be any major changes in our nation's gun laws. And Missouri is certainly worth watching in the days and weeks ahead.