California governor Gavin Newsom (D.) announced a plan Thursday to amend the U.S. Constitution to add gun-control measures.

Newsom tweeted out his proposal to ban so-called assault weapons and enact universal background checks, a minimum firearm-purchasing age of 21, and a mandatory waiting period. He also said states could enact further gun control on top of what his amendment would require nationwide. 

“The 28th Amendment permanently enshrines four additions to the laws of our land,” Newsom said in the video. “This will guarantee states as well the ability to enact common-sense gun safety laws while leaving the Second Amendment intact and respecting America’s gun-owning tradition.”

Newsom’s proposal comes in the wake of gun-rights advocates winning a string of federal court cases. In New York State Rifle and Pistol Association v. Bruen last summer, the Supreme Court ruled New York’s criteria for concealed carry to be unconstitutional and set a new standard for how courts should decide Second Amendment cases. Since then, dozens of successful Second Amendment cases have weakened gun-control regimes around the country.

California has some of the strictest gun laws in the country. It is one of only a handful that already has all four gun policies included in the proposed amendment. According to Giffords, 21 states require background checks for all gun sales. 10 states, including California, currently impose a minimum age of 21 for gun purchases. 10 and the District of Columbia have implemented waiting periods on gun sales or assault weapons bans, and those bans often define what constitutes an “assault weapon” differently.

In his video, Newsom cited Fox News polling data from April to argue citizens across all parties support his proposals. However, a Monmouth poll also released in April found only 46 percent of Americans favored banning assault weapons—15 percentage points below Fox’s number. And polls from Quinnipiac University and ABC News/Washington Post months before also found more Americans opposed such a ban than favored one.

The courts have also produced mixed results on the constitutionality of assault weapons bans to this point. Federal judges in Colorado and Illinois have found the bans violate the Second Amendment. However, another federal judge recently ruled against gun-rights advocates seeking a preliminary injunction against the state of Washington’s assault-weapons ban. Last month, the Supreme Court decided against intervening in a case regarding the Naperville, Illinois, ban on AR-15s. That indicates the legal fight over the bans is not over.

Newsom argued it is necessary to raise the minimum age for firearm purchases “because if you can’t buy a beer, you shouldn’t be able to buy a gun.” His call for universal background checks is “to prevent truly dangerous people from purchasing a gun that can be used in a crime.”

The proposed amendment faces an arduous journey and extremely long odds to potential ratification.

Newsom is calling for two-thirds of state legislatures to follow California in calling for a constitutional convention, which they would need just to propose the language of the amendment. If the convention occurs and an amendment is successfully proposed, then three-fourths of state legislatures need to ratify the amendment. The Constitution hasn’t been amended in over thirty years.

Newsom admitted in his video, “this fight won’t be easy, and it certainly won’t be fast.”

UPDATE 6-10-2023 7:22 PM EASTERN: This piece has been updated to conform the state law estimates with those posted by Giffords.