TALLAHASSEE, Fla. — The political and legal fallout from Florida Gov. Rick Scott's decision to sign a sweeping gun bill into law following a school massacre was nearly immediate as the National Rifle Association filed a lawsuit to stop it and political candidates in both parties criticized it.

Republican U.S. Rep. Ron DeSantis, who's running for Florida governor as a champion of gun rights, went on Fox News late Friday night to criticize the law, which raises the minimum age to buy rifles from 18 to 21; extends a three-day waiting period for handgun purchases to include long guns; and bans bump stocks, which allow guns to mimic fully automatic fire.

"I think when you start getting into some of the blanket restrictions on people's Second Amendment rights, I think that that is constitutionally vulnerable. ... I mean think about it, you have an enumerated right in the Bill of Rights, there's really no precedent to just do a blanket ban on certain adults," DeSantis said on the show.

Grieving families and student survivors from Marjory Stoneman Douglas High School in Parkland, where a shooter killed 17 people last month, worked feverishly in recent weeks to lobby a gun-friendly, Republican-run state government. The new law fell short of achieving a ban on assault-style weapons, but it creates a so-called guardian program enabling some teachers and other school employees to carry guns.

Five legislators seeking statewide office voted against it, as did the chairman of the Republican Party of Florida. GOP Attorney General Pam Bondi praised it, but other statewide candidates in the Legislature voted against it. Commissioner of Agriculture Adam Putnam has expressed his displeasure with the age limits.

Scott, who's expected to challenge Democratic U.S. Sen. Bill Nelson this year, has said the legislation shows Florida can move quickly and "get things done," unlike the federal government. Scott has already blasted Nelson for failing to act on guns while he's been in Congress.

Democrats, meanwhile, were quick to fault Scott and legislators for failing to include a ban on some types of semi-automatic rifles such as the one used in the Parkland shootings.

Tallahassee Mayor Andrew Gillum said that "Florida's elected officials simply have not done enough to stop our gun violence epidemic, and that remains true even with the Governor's signature today."

Miami Beach Mayor and Democratic gubernatorial candidate Philip Levine said in a statement the law "falls short of the public demands set by the majority of Floridians and the student survivors" of the shooting. "We need to ban assault weapons, pass universal background checks, and we certainly don't need more guns in our schools."

Separately, the Trump administration on Saturday said it has taken the first step in the regulatory process to ban bump stocks.

The NRA contends the new law is unconstitutional because it raises the minimum age to buy rifles and puts a blanket ban on the fundamental rights of some law-abiding Florida citizens.

"The deranged murderer in Parkland, Florida, gave repeated warning signs that were ignored by federal and state officials. If we want to prevent future atrocities, we must look for solutions that keep guns out of the hands of those who are a danger to themselves or others, while protecting the rights of law-abiding Americans," said Chris W. Cox, executive director, National Rifle Association Institute for Legislative Action.

Retired prosecutor and Florida law professor Bob Dekle sees no legal issue with raising the rifle-purchase age to 21, saying, the framers of the Constitution intended for 21 to be "the age of being adult." He noted that the same age applies to voting and drinking.

"This lawsuit I think is an example of bonkers," said Dekle, who plans to leave the NRA as soon as his membership expires. "The 21-year age limit just sounds reasonable to me."

Stoneman Douglas student Talia Rumsky, 16, called the law a positive change, but said there's "still a long way to go."

"As happy as I am that Governor Scott signed it, this cannot be the last preventative measure he helps pass ... My friends and I were upset to hear that the amendment to ban AR-15s for even just two years ... did not pass, especially since this weapon has been used in not just one, but several horrific mass shootings," she said in a text.

Students also criticized the provision allowing teachers to have guns on campus. The Broward County school superintendent has already said he doesn't want to participate in the program.

"You said you were against teachers being armed. We told you we were against it. So why didn't you stop that part," tweeted student Aly Sheehy Friday, referring to Scott. "Don't stand there and say you disagree with it when you hold the power to put an end to it."

Nikolas Cruz , the 19-year-old former student accused in the school massacre, faces 17 counts of murder and attempted murder. Cruz's public defender has said he will plead guilty if prosecutors take the death penalty off the table and sentence him to life in prison instead. Prosecutors have not announced a decision.