A Democratic U.S. Senator from Oregon supports legalizing the recreational use of marijuana and will vote "yes" to a state initiative next week that would let adults consume pot for fun, his office said on Monday.

But a staffer for Senator Jeff Merkley said her boss had stopped short of officially endorsing an Oregon ballot initiative that would legalize, regulate and tax non-medical marijuana and permit its use by adults over age 21.

"The senator has not endorsed the ballot measure, but he has said he will vote for it," said Courtney Warner Crowell, Merkley's deputy communications director.

The support makes Merkley the first sitting senator to publicly support legal recreational pot, according to a round-up of U.S. politicians' views on the topic updated on Monday by Huffington Post.

Washington state and Colorado this year became the first two U.S. states to permit recreational sales of marijuana.

Oregon voters will have a second chance in the Nov. 4 general election to legalize recreational marijuana, after a 2012 effort failed at the ballot box. Voters in Alaska and Washington, D.C., will also vote on recreational marijuana.

A DHM Research poll released Oct. 14 showed this year's Oregon measure leading with 46 percent of likely voters in favor versus 36 percent against. The poll, of about 500 likely voters, was conducted Oct. 8 to 11 and had a margin of error of 4.3 percent.

The move comes about a month after a former U.S. attorney for Oregon, Kris Olson, endorsed the upcoming referendum to legalize recreational marijuana, saying laws banning the drug have failed to curb its use.

U.S. Representative Earl Blumenauer, a Democrat, and former Oregon Supreme Court Justice Bill Riggs have also both spoken out in favor of legalization.

Possession of marijuana is illegal under federal law, but the U.S. Justice Department has said it will not intervene in states with "strong and effective regulatory and enforcement systems."