DENVER - The Colorado Senate passed the marijuana DUI limit of 5 nanograms per milliliter of marijuana's psychoactive ingredient, THC.

Governor John Hickenlooper campaigned hard for this bill.

The bill was overly popular in the Senate with a two-thirds majority.

A vote in the Senate Appropriations Committee on Monday afternoon was at least the fifth time the Senate, or a Senate committee, had rejected the pot-driving limit.

It is already illegal to drive while impaired in Colorado, and opponents to the blood threshold said officer observation should be the basis for stoned-driving cases.

Many senators questioned whether a blood limit for marijuana, which is processed by the body differently than alcohol, is a fair measure of driving impairment.

"I just do not have enough information to make me feel comfortable on making a decision like that one," said Sen. Cheri Jahn, D-Wheat Ridge.

Senators had resisted even direct pleas from the Democratic governor to stop fighting the blood standard.

When a driving-high bill was rejected in another Senate committee earlier this year, Gov. John Hickenlooper took the unusual step to taking to Twitter to urge the blood standard's approval. The only other state to legalize pot for recreational use, Washington, already has a voter-approved threshold of 5 nanograms.

The Colorado House planned to keep fighting for the limit. The House passed a bill Monday to revive the driving standard, forcing yet another showdown with the Senate.