The group that put medical marijuana on the Florida ballot this year — and fell just short of passing it — intends to launch a new constitutional amendment campaign shortly.

"We are swiftly mobilizing a new petition push to get medical marijuana" on the next general election ballot, United for Care director Ben Pollara told supporters this week in a fundraising announcement.

A constitutional amendment would not be necessary if the Legislature approves medical marijuana by statute, but "we cannot rely on that," Pollara said. "We are going to pass a medical marijuana law in Florida by the end of 2016."

Amendment 2 — this year's version — gained 58 percent of the vote, just shy of the required 60 percent. It would have allowed patients with debilitating illnesses to possess pot with a doctor's recommendation.

Pollara said in an interview that United for Care's lawyer is tweaking Amendment 2's ballot language to bolster areas that opponents attacked.

One section will say explicitly that minors cannot get pot without their parents' consent.

Another section will specify that the amendment does not change existing laws about negligence by patients and doctors.

The adjective "debilitating" will be stressed more when describing qualifying conditions.

A Florida Supreme Court opinion in January should have made clear that Amendment 2 already covered such issues, Pollara said. But since opposing arguments on these points did sway some voters, he said, United for Care intends to be more explicit the second time around.

Representatives of St. Petersburg's Drug Free America Foundation, a key opponent of the ballot initiative, did not respond to requests for comment Wednesday.

Orlando lawyer John Morgan will once again lead the amendment campaign, Pollara said. Morgan could not be reached Wednesday.

To put a new constitutional amendment on the next general election ballot, United for Care has until January 2016 to submit petitions signed by nearly 700,000 voters.

Seeking as much lead time as possible, the organization will begin collecting signatures as soon as the ballot language is set, Pollara said, probably "within the next few weeks."

Last time, United for Care cranked up its petition drive in earnest only a few months before the deadline and Morgan ended up spending more than $4 million on professional signature gatherers. At one point, he said, he was paying $8 per signature.

Now United for Care has contact information for the people who signed the 2014 petition and more time to work with.

"We expect 2016 to be significantly less expensive," Pollara told supporters, "and allow us to budget a lot more for statewide advertising" to pass the amendment.

He predicted that passage would be easier, because the 2016 presidential vote will drive up turnout. Younger people, the strongest supporters of medical pot, typically vote in higher numbers in a presidential year.

While United for Care campaigns for a new amendment, he said, the group's lobbying spinoff — Florida for Care — will try to persuade the Legislature to pass a full-fledged medical marijuana system. This year's approval of a noneuphoric pot known as Charlotte's Web is a far more limited approach than what is being sought.

"If we get a decent law," Pollara said, "maybe 75 or 80 percent of what we want, we won't have to go back to the ballot."

Contact Stephen Nohlgren at nohlgren@tampabay.com.