(CNN) Former Rep. Beto O'Rourke called for the legalization of marijuana nationwide Monday in an email to supporters that comes ahead of an expected bid for the 2020 Democratic presidential nomination.

The former Texas congressman's call came as part of a series of criminal justice proposals he said would "build a criminal justice system that is more fair and that urgently puts our country closer to the words written above the highest court in our land: equal justice under law."

His lengthy email -- to the massive list he leveraged to raise $80 million in last year's Senate contest -- detailing the series of criminal justice reforms is a sign that O'Rourke is beginning to roll out a policy platform ahead of a 2020 presidential campaign.

He said in a statement last week that he'd made up his mind about whether to run for president. His aides began discussing staff roles on a presidential campaign with Democratic operatives, a source familiar with the matter said.

He said the federal prohibition on marijuana usage should be repealed and the records of those incarcerated for marijuana possession expunged -- an idea advocated last year by New Jersey Sen. Cory Booker that's since been endorsed by most of the Democratic 2020 prospects.

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