Top legislative leaders from both parties were pessimistic Friday about chances that medical marijuana would be legalized this year, even after Gov. Mark Dayton put new weight behind finding a compromise on the controversial bill.

A day earlier, Dayton abruptly shifted on the issue after a two hour meeting with medical marijuana advocates. After downplaying the proposal's chances Thursday morning, Dayton instructed his chief of staff and health commissioner to find a compromise on Thursday afternoon.

But at a Friday news briefing, House Majority Leader Erin Murphy declared it "probably not possible to get this conversation done yet this session." House Speaker Paul Thissen and Deputy Senate Majority Leader Jeff Hayden, both DFLers from Minneapolis, echoed her pessimism.

"There may be a more fruitful discussion that happens after this session into next year, that will yield a better outcome on this issue for Minnesotans," said Murphy, DFL-St. Paul.

While law enforcement objections to the proposal have been widely aired, Murphy said she wanted to see more input from the medical community.

Police and sheriffs have long argued that legalizing marijuana for patients who get a doctor's prescription would make illegal uses of the drug harder to control, and open the door to full-scale legalization.

The issue has scrambled partisan lines at the Capitol, with both Democrats and Republicans on both sides of the debate.

Senate Minority Leader David Hann, R-Eden Prairie, said Friday he thinks marijuana could be beneficial for some patients; but said the lack of consensus in the medical community "could put pharmacists and medical professionals in tough positions."

Dayton instructed a handful of top staffers and Health commissioner to meet with advocates and other concerned groups to see if there's still room for compromise.

Dayton spokesman Matt Swenson said Friday that the governor's chief of staff, Jamie Tincher, is working on setting up those meetings.

Photo: Medical marijuana advocates demonstrate outside Gov. Mark Dayton's residence in St. Paul. Souce: Star Tribune.