(The Center Square) - President Joe Biden Thursday pardoned thousands of people convicted under federal law of simple marijuana possession and urged governors around the country to do the same with state offenses.

Not all governors, however, have such unilateral authority.

The proclamation specified it applied to only the "offense of simple possession of marijuana."

The Libertarian Party estimated the pardon would affect about 6,500 people.

"As I often said during my campaign for president, no one should be in jail just for using or possessing marijuana," Biden said in a statement. "Sending people to prison for possessing marijuana has upended too many lives and incarcerated people for conduct that many states no longer prohibit."

Biden said he's also asking the secretary of Health and Human Services, Xavier Becerra, and Attorney General Merrick Garland to review how marijuana is regarded under federal law. Biden said marijuana is considered the same class of drug as heroin and LSD and is on a higher schedule of classification than fentanyl and methamphetamine.

The Department of Justice released a statement saying it would launch a "scientific review" of how marijuana is scheduled under federal law.

The Democratic political action committee MeidasTouch said the pardon was historic.

"President Biden pardoning all prior federal offenses of simple marijuana possession may just be the single-most transformative, morally right, politically smart use of the pardon power in history. It's impossible to overstate just how massive this news is," MeidasTouch posted on Twitter.

Occupy Democrats tweeted it was the "greatest presidential mass pardon in history." 

The move comes just more than four weeks before Election Day. Analysts quickly seized on the announcement as a plea to voters, especially younger voters and those of color.

Biden's announcement does not decriminalize marijuana under federal law. In 1970, the Controlled Substances Act made it what is labeled Schedule 1. This means it has “no currently accepted medical use and a high potential for abuse.” Many states have since made all uses of marijuana legal, and others have made medical marijuana legal.