DOVER — The House of Representatives did not vote on a controversial assisted suicide bill Thursday, the second time in three months the measure has been yanked from the agenda.

House Bill 160 would allow a mentally competent adult with a terminal disease — defined as “an incurable and irreversible disease that has been medically confirmed and will, within reasonable medical judgment, produce death within six months” — to end his or her life with the aid of a doctor.

Known as the Delaware End of Life Options Act, the measure was introduced by Rep. Paul Baumbach, D-Newark, last year. It was pulled from the agenda Thursday because at least one legislator backed off, bringing the side in favor to fewer than 21 votes. The same thing happened in January.

Despite that, Rep. Baumbach remains hopeful.

“We came up short today, so we’ll hold off and keep it on the ready list and see what the coming weeks bring,” he said.

The measure carries several safeguards, such as requiring a doctor to confirm the individual in question is dying and is not suffering from any mental illness or condition. It also mandates the patient request the medication three times and imposes a 15-day waiting period between the first and second oral request and a two-day delay between the final request and the writing of the prescription.

But those aren’t enough for many. Some individuals object to the idea of ending a life, while others fear the proposal could lead to individuals with serious illnesses or disabilities being pressured to end their lives — or even terminated without their consent.

Diann Jones, of Middletown, was one of a handful of people who came to Legislative Hall to oppose the bill Thursday.

“I think it devalues people who have disabilities, first of all. I think we should be concentrating on life, palliative care, supporting people at the end of their life, instead of making decisions that we should assist in suicide,” she said.

The word “disability” appears only once in the bill: “No person can qualify under the provisions of this chapter solely because of age or disability.”

Ms. Jones, herself a cancer survivor, noted some people given just a few months to live far outlast that diagnosis. She also took issue with the bill mandating the cause of death be listed as the underlying illness, rather than assisted suicide.

But opponents weren’t the only ones who flocked to the state capitol to press lawmakers on the bill.

About 20 advocates showed up for the planned vote, including representatives of Compassion & Choices, a nonprofit that, per its website, supports “medical aid in dying to allow mentally capable adults in their final weeks or months of a terminal disease to advance the time of death and end unbearable suffering.”

Tim Appleton, multi-state campaign and outreach manager for the group, said he is confident momentum is growing for the cause.

“It’s necessary because people every day come to us from Delaware — from Wilmington, from Lewes, from Dover — and they ask us, ‘How can we help out?’ And the reason they ask isn’t a policy reason, it’s a personal reason. They want these options for themselves,” Mr. Appleton said, describing passage as “inevitable.”

Six states currently have assisted suicide laws.

Oregon, the first state to legalize physician-assisted suicide, reported in 2016 that since the law went into effect in 1997, 1,749 people received medication. Of those, 1,127 opted to use it to end their lives.

Gov. John Carney opposes the bill, according to a spokesman.