A ballot measure that would have enshrined abortion rights in the Florida Constitution failed Tuesday, NBC News predicts, after a political battle that was among the most hotly contested in the state this election cycle.

The amendment received majority support from Florida voters but had to pass the 60 percent threshold to pass under state law. Their defeat is a setback for groups advocating for reproductive rights in the red-leaning state and a victory for Republican Gov. Ron DeSantis, who fought fiercely against the initiative.

The proposal, known as Amendment 4, sought to allow abortions in Florida until fetal viability, which is approximately 24 weeks of pregnancy. Under a law signed by DeSantis, abortions after six weeks of pregnancy are banned in the state.

Decades before the U.S. Supreme Court ruled on Roe v. Wade repealed, fetal viability was the standard for the state's abortion law.

DeSantis' opposition to the proposal, brought to a vote by the abortion rights group Floridians Protecting Freedom, sparked vocal criticism and legal challenges over allegations that he improperly used government resources in a political matter.

A state agency in the DeSantis administration had launched a website Attacking the ballot measure, a move that drew a lawsuit from the American Civil Liberties Union.

“In educating the electorate about the purpose and effects of a proposed constitutional amendment, the government must not do so in an inaccurate, misleading, abusive or fraudulent manner,” says the lawsuit filed in September. The state’s “actions regarding Amendment 4 were inaccurate, misleading, abusive and fraudulent.”

State agencies under DeSantis' control also used taxpayer money to produce and buy campaign-style television ads sharply criticizing the proposal, a move that further fueled critics' concerns that state funds were being used inappropriately.

The DeSantis administration also sent letters threatening state television stations with criminal charges if they aired political ads supporting the change, a move rebuked by Federal Communications Commission Chairwoman Jessica Rosenworcel.

“Broadcasters’ right to speak freely is enshrined in the First Amendment,” wrote Rosenworcel, a Democrat. “Threats against broadcasters for broadcasting content that contradicts the government’s views are dangerous and undermine the fundamental principle of freedom of expression.”

Generally, government funds are not used for overt campaigning or political purposes, but the effort proved successful for DeSantis as the courts did not intervene and did not prevent state agencies from engaging in the political fray.

With Florida's status as a swing state quickly fading, the fight over Amendment 4 sparked by far the largest wave of television advertising in the 2024 election cycle.

Although the ballot measure failed, the NBC News exit poll found that 65% of Florida voters thought abortion should be legal in all or most cases.

Another ballot measure DeSantis opposed, an attempt to legalize recreational marijuana use in Florida, also failed Tuesday, NBC News predicted. Voters' rejection of both measures represents a major political victory for DeSantis, who limped after his presidential bid ended abruptly this year following a loss in the Iowa caucuses.