Advocates for local autonomy in the District of Columbia are vowing to fight any effort by Congress to undo the District’s recent liberalization of marijuana laws.timthumb

Democratic Mayor Vincent Gray signed a bill in March that decriminalizes possession of small amounts of pot. The bill would become law in July if Congress doesn’t intervene.

District advocates say Rep. Andy Harris, a Maryland Republican, plans to introduce an amendment to a spending bill on Wednesday that would block the nation’s capital from implementing the new marijuana law.

Del. Eleanor Holmes Norton, a Democrat who represents the District in Congress, says Harris “is acting contrary to the laws of his own state,” which recently decriminalized marijuana. It’s one of 18 states that have some form of decriminalization.