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

The amendment won majority support from Florida voters, but it needed to cross the 60% threshold to pass under state law. Its defeat is a setback for reproductive rights groups in the red-leaning state and a victory for Republican Gov. Ron DeSantis, who had campaigned heavily against the initiative.

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

For decades before the U.S. Supreme Court overturned Roe v. Wade, fetal viability was the standard for the state’s abortion law.

DeSantis’ opposition to the proposal, which was placed on the ballot by the abortion-rights group Floridians Protecting Freedom, drew vocal criticism and legal challenges over allegations he was improperly using state resources in a political matter.

A DeSantis administration state agency 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 ramifications of a proposed constitutional amendment, the government cannot do so in a manner that is inaccurate, misleading, abusive, or fraudulent,” read the lawsuit, filed in September. The state’s “actions regarding Amendment 4 have been inaccurate, misleading, abusive and fraudulent.”

State agencies under DeSantis’ control also used taxpayer dollars to produce and purchase campaign-style TV ads blasting the proposal, a move that further fueled critics’ concerns that state resources were being used inappropriately.

The DeSantis administration also sent letters threatening state TV stations with criminal charges if they aired political ads supporting the amendment, a move that drew rebuke from Federal Communications Commission Chairwoman Jessica Rosenworcel.

“The right of broadcasters to speak freely is rooted in the First Amendment,” Rosenworcel, a Democrat, wrote. “Threats against broadcast stations for airing content that conflicts with the government’s views are dangerous and undermine the fundamental principle of free speech.”

Generally, state resources are not used for overt campaign or political reasons, but the effort proved successful for DeSantis, as the courts did not step in and stop state agencies from engaging in the political fight.

With Florida’s status as a swing state fading fast, the fight over Amendment 4 drew by far the biggest wave of TV ads during the 2024 election cycle.

Even though the ballot measure failed, the NBC News Exit poll found that 65% of Florida voters said abortion should be legal in all or most cases.

Another ballot measure DeSantis opposed, the effort to legalize the use of recreational marijuana in Florida, also failed Tuesday, NBC News projected. Voters' rejection of both measures mark a huge political win for DeSantis, who was left limping after his presidential bid ended abruptly this year after a loss in the Iowa caucuses.