Tennessee lawmakers have abruptly delayed all efforts to legalize medical marijuana until next year, abandoning several bills moments before the controversial topic was expected to be debated for the first time.

Sen. Steve Dickerson, a doctor who is one of the biggest advocates in the Tennessee legislature for medical marijuana, said during a Senate hearing Wednesday he was regrettably delaying all bills involving cannabis until 2020. The House also had rolled the bills until next year, Dickerson said.

Less than an hour before that hearing, Dickerson had intended to amend an existing bill to introduce a detailed proposal to legalize and regulate medical marijuana throughout Tennessee.

But the senator said he was convinced the bill would fail shortly before the hearing began, and decided it was better to delay the proposal than watch it fail in committee.

“You can run a bill and have it defeated, or you can keep it alive," Dickerson told the USA TODAY Network - Tennessee. "And practically speaking, we decided to keep it alive and not have a defeat for perception more than anything."

The medical marijuana legislation that was expected to be discussed in the Senate Health and Welfare Committee on Wednesday would have been the most robust proposal of its kind currently before the legislature, and most likely the most complete proposal ever introduced in Tennessee.

The bill proposed creating a legal infrastructure for the government to issue medical marijuana cards and license marijuana farms, processors and dispensaries.

Residents would have been eligible for a card only if they had been diagnosed with a “debilitating medical condition,” including cancer, post-traumatic stress disorder, HIV/AIDS or severe arthritis. The sale of medical marijuana could have started as soon as summer 2020 if the proposal had advanced.

The bill would have allowed for marijuana vapes, edibles, oils and lotions, but not smoking.

The primary sponsors were set to be Dickerson, R-Nashville, and Rep. Bryan Terry, R-Murfreesboro, both of whom are doctors. But the bill also was backed by many of the legislature’s most prominent medical marijuana supporters, including Sen. Janice Bowling, R- Tullahoma; Rep. Ron Travis, R-Dayton; and Rep. Jeremy Faison, R-Cosby.

The delay of these bills closely mirrors what happened last year, when some of the same lawmakers introduced medical marijuana legislation, then withdrew it during committee in April due to lack of support.

During the hearing Wednesday, Dickerson said he felt the issue kept falling short “on the precipice” of success.

“I believe facts will win out," Dickerson said. "I believe Tennessee will soon embrace medical cannabis, but unfortunately not soon enough for many of my patients, many of our friends and people in the audience."

Brett Kelman is the health care reporter for The Tennessean. He can be reached at 615-259-8287 or at brett.kelman@tennessean.com. Follow him on Twitter at @brettkelman.