DENVER — Marijuana activists in Colorado are hoping for another last-minute victory in their battle against blood-level limits for drivers.

A bill setting a blood standard for THC, the psychoactive ingredient in marijuana, cleared the House Tuesday and is pending in the Senate. Marijuana activists are fighting the proposal because they say blood THC tests are an unfair gauge of impairment. Sponsors of the bill say more drivers are using marijuana and that the state needs a marijuana analogy to the accepted blood-alcohol limit.

The pot activists have prevailed twice, but the measure is back before lawmakers in a special legislative session expected to end Wednesday. Marijuana activists hope to sink the third attempt when the bill hits a debate in the Senate.