WASHINGTON (Reuters) - Cory Booker has reintroduced his U.S. Senate bill to legalize marijuana at the federal level. Beto O’Rourke called for expunging the records of those arrested for possession of the drug. Kamala Harris admitted she had smoked pot - and inhaled.

FILE PHOTO: Protesters gather to smoke marijuana on steps of the U.S. Capitol to tell Congress to "De-schedule Cannabis Now", in Washington, U.S. April 24, 2017. REUTERS/Yuri Gripas/File Photo

When it comes to legalizing marijuana, many of the current and potential 2020 Democratic presidential contenders are eager to show they are cool with cannabis.

Their embrace of the issue reflects a rapid shift in public opinion that has brought what was once an extreme political position into the mainstream.

A Gallup poll in October found two of every three Americans support legalization, a record high, and for the first time a slim majority of Republicans support legal marijuana. Three of every four Democrats back legalization.

Ten states and the District of Columbia now allow legal recreational use and more than 30 states have legalized it for medical use.

“The Democratic candidates are just acknowledging the practical and political reality - this is not only good policy, it’s good politics,” said Erik Altieri, executive director of the National Organization for the Reform of Marijuana Laws.

Booker has led the charge, reintroducing his Senate bill last week for federal legalization. Four fellow senators and 2020 Democratic presidential candidates are co-sponsors: Harris, Kirsten Gillibrand, Bernie Sanders and Elizabeth Warren.

The other declared White House candidate in the Senate, Amy Klobuchar, has not co-sponsored Booker’s bill but said in a statement she supported legalization.

Most other contenders also have taken public stands in support of some degree of legalization, with many linking the issue to criminal justice reform and protesting that racial minorities are disproportionately arrested for possession and hit with harsh sentences.

“We should end the federal prohibition on marijuana and expunge the records of those who were locked away for possessing it, ensuring that they can get work, finish their education, contribute to the greatness of this country,” O’Rourke, the former Texas congressman who is expected to announce soon whether he will run, said in an email to supporters on Monday.

SEA CHANGE

The shift in political attitudes has come quickly for presidential candidates. During his 1992 run to the White House, Democrat Bill Clinton famously said he had tried pot but “didn’t inhale.”

Hillary Clinton opposed federal legalization in 2016 but supported letting states decide their own approach. Republican President Donald Trump also said during the campaign he would let states chart their own course and later undercut plans by his former attorney general, Jeff Sessions, to crack down on states that legalized marijuana.

Harris, a former California attorney general and San Francisco prosecutor, opposed a California ballot initiative in 2010 that would have legalized marijuana. The initiative failed.

But as a presidential candidate, she joked recently about smoking pot, telling a New York radio show that “I inhaled,” and adding: “Half of my family’s from Jamaica. Are you kidding me?”

The two governors in the Democratic race, Jay Inslee of Washington and former Colorado Governor John Hickenlooper, are intimately familiar with the issue. Their states were the first to legalize recreational marijuana use.

“It’s time for Congress to acknowledge that marijuana legalization is working in states like Washington, Colorado, and others and legalize marijuana as well,” Inslee, who plans to pardon thousands of people convicted of small-time possession charges, said on Twitter in October.

Hickenlooper has been more measured, saying states should be free to legalize and the federal government should make changes to accommodate that choice such as changing federal banking laws.

Sanders, during his failed 2016 Democratic primary run against Clinton, was the first high-profile presidential candidate to support federal legalization.

“Too many lives are being destroyed. Hundreds of thousands of people get criminal records. You know why? Because they have smoked marijuana,” Sanders said on a radio talk show on Monday. When asked, he said he had tried marijuana.

“It didn’t do a whole lot for me,” he said, adding he “nearly coughed my brains out.”