ALBANY — The Republican majority in the State Senate is not satisfied with a proposal by Gov. Andrew M. Cuomo to decriminalize the open possession of small amounts of marijuana and will not pass it in its current form, the chamber’s top lawmaker said Wednesday.

The lawmaker, Senator Dean G. Skelos, who is the majority leader, suggested that the proposal, which would reduce the open possession of 25 grams or less of marijuana to a violation from a misdemeanor, was overly broad and would effectively condone the practice of carrying around marijuana.

“Being able to just walk around with 10 joints in each ear, and it only be a violation, I think that’s wrong,” Mr. Skelos, pointing to his ears, told reporters.

The Senate is the primary obstacle facing the decriminalization proposal, which the Assembly speaker, Sheldon Silver, a Manhattan Democrat, has endorsed. Still, the decision by Mayor Michael R. Bloomberg, Police Commissioner Raymond W. Kelly and prosecutors to endorse the measure improves the chances that a deal will be negotiated before the scheduled end of the legislative session, on June 21.