Veterans in states where medical marijuana is legal would be able to discuss the drug as a treatment option with Veterans Affairs doctors for the first time under an amendment added to the VA's fiscal 2016 budget on Thursday.

The measure passed the Senate Appropriations Committee by an 18-12 vote, with several Republicans backing the idea. Earlier this month, a similar proposal failed to pass during House debate on the budget bill, by a 213-210 tally.

The marijuana proposal still must survive a full Senate vote and a conference with House lawmakers before it could be sent to President Obama to become law, a difficult path given majority Republicans' past objections to the idea.

But Thursday's vote was hailed by pro-marijuana advocates as a significant step forward. Officials from the Drug Policy Alliance called it an opportunity for veterans to finally enjoy "full and open discussions with their doctors" about treatment options.

Use of marijuana for treating various medical problems has been a controversial topic in the veterans community. While some insist on its value in treating post-traumatic stress disorder and in pain management, VA officials note that no studies support its use for war injuries.

But Senate advocates — including presidential candidate Sen. Rand Paul, R-Ky. — have argued that lack of research is due in part to existing laws labeling marijuana as a potentially dangerous controlled substance.

Thursday's measure, sponsored by Sens. Jeff Merkley, D-Ore., and Steve Daines, R-Mont., would allow VA physicians to discuss use of the drug for pain management or anxiety only in the 24 states where the drug is legal, either for medical or recreational purposes.

Such conversations would not be allowed in states where possession of marijuana is still a crime, leading several committee members to express concern that the differing rules could lead to inconsistent federal policy.

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But supporters said the measure is about finding the best available treatments for veterans, and answering questions that are coming up more frequently between VA doctors and their patients.

The VA appropriations bill is expected to be voted on by the full Senate this summer. Lawmakers from both chambers hope to finalize a compromise budget bill in early fall.