ORLANDO, Fla. — In Tampa, the top prosecutor says too many children are charged as adults. In Houston, the district attorney will no longer press charges in low-level marijuana cases. And in Chicago, prosecutors will no longer oppose the release of many nonviolent offenders who cannot afford to post bond.

Two more newly elected prosecutors, in Denver and Orlando, have vowed not to seek the death penalty, even for the most egregious killers.

They are part of a new vanguard that has jettisoned the traditional lock-’em-up approach, instead winning over voters by embracing alternatives to harsh punishment. But in their eagerness to enact changes, some are facing a backlash from law enforcement groups and more conservative politicians.

In Texas, Lt. Gov. Dan Patrick, a Republican, warned that failing to punish drug crimes would make Houston akin to a “sanctuary city” for illegal enterprise. In Chicago, a suburban police chief warned that a move to classify more shoplifting cases as misdemeanors was “a slippery slope.”

But nowhere has there been more vitriol than in Florida, where a battle over the death penalty shows just how volatile an issue capital punishment remains, especially when the death of a police officer is involved.

Aramis D. Ayala, the new chief prosecutor in Orlando and a Democrat, announced on March 16 that she would no longer seek the death penalty. Almost immediately, Gov. Rick Scott, a Republican, moved to replace her in the case of Markeith Loyd, who is charged with killing his pregnant ex-girlfriend and, during a subsequent manhunt, an Orlando policewoman. “Every citizen should be outraged,” he said of the decision of Ms. Ayala, a Democrat.

This week, state legislative committees proposed cutting her budget by more than $1 million, saying it was to cover the costs of other jurisdictions that are assigned her capital cases. Some lawmakers are now calling for her suspension. On Thursday, Ayala supporters from across the state will travel to Tallahassee for a rally, while her opposition is set to protest in Orlando.

In court papers, Ms. Ayala, the state’s first black elected prosecutor, said removing a prosecutor because of a disagreement over her use of discretion was “unprecedented.” The NAACP, the Florida Legislative Black Caucus and other groups denounced the governor’s intervention, with one caucus member calling it “a lynching.”

On Tuesday, Ms. Ayala appeared in court to argue for a delay while she fights Mr. Scott’s order. She was represented by Roy L. Austin Jr., a former Obama White House official who also served as a high-ranking civil rights lawyer for the Justice Department. Florida law allows the governor to appoint a special prosecutor in cases where he finds “good and sufficient reason” that “the ends of justice would be best served.”

Still, Mr. Austin said the governor had overstepped. “I don’t know how she is expected to operate with him deciding which cases he is going to take off of her hands or not,” he said.

Chief Judge Frederick J. Lauten of the Ninth Circuit Judicial Court denied her request, saying that Mr. Scott’s order should be presumed legal.

Ms. Ayala is adamant that her moratorium on the death penalty was not based on emotion, but rather on research that shows that states with capital punishment are no safer than states without it.

She said she could not look victims’ relatives in the eye and promise an execution while knowing that the inmate would in all likelihood appeal for decades.

Ms. Ayala, 42, said one of the inmates on death row in her state was convicted when she herself was just 2 years old.

“This is not a moral decision; it is not a personal opinion,” she said. “When I look at this, it’s the right decision based on the facts.”

Beth McCann, the Denver prosecutor who made a similar commitment to end capital cases, said Ms. Ayala’s decision took particular courage because she had death penalty cases pending when she took office. Denver did not.

“I, for many years, personally felt the state shouldn’t be in the business of killing people,” Ms. McCann said. “I’m the only district attorney in Colorado who has publicly said they will not bring the death penalty, although I know there are some who share my view.”

Statistics suggest that she is right: Many prosecutors have made the same decision, they just have not said so out loud.

Death sentences were handed down in only 27 counties nationwide last year, compared with 60 in 2012, according to the Death Penalty Information Center, a nonprofit research group that opposes capital punishment.

In part, this has been driven by the increasing reluctance of jurors to impose capital punishment, which in turn has made fewer prosecutors willing to go through the enormous trouble and expense of seeking it.

In Raleigh, N.C., six back-to-back juries gave life sentences to killers whom prosecutors had sought to execute, prompting Lorrin Freeman, the Wake County district attorney, to say last year, “I do think at some point we have to step back and say, ‘Has the community sent us a message on that?’”

Her office sought capital punishment in two more cases this month, but again, the jury declined. Ms. Freeman has said she will continue to weigh the death penalty case by case.

The new breed of prosecutors was helped into office by voters skeptical of wrongful convictions, mass incarceration and evidence of racial bias in law enforcement. As candidates, many received help from the liberal billionaire George Soros, who spent millions on campaigns in states including Arizona, Mississippi and Missouri. Of the 15 candidates supported by his political action committees (including one for sheriff), 12 were victors.

But some change-minded prosecutors won without Soros money, showing that attitudes across the country are changing regardless of outsize political contributions, said David A. Sklansky, a professor at Stanford Law School who closely follows the issue.

“It’s now possible in at least some places for district attorneys to campaign successfully and win office on a platform that’s not just harsher, harsher, more, more punishment,” he said. “That was unheard-of 10 years ago.”

Bob Ferguson, the attorney general of Washington State, said, “I think our public’s view of our criminal justice system has evolved.” Speaking out against the death penalty, he added, “is not the third rail people think it is.”

In January, Mr. Ferguson, a Democrat, was joined by his Republican predecessor, Rob McKenna, in calling for the state Legislature to abolish capital punishment. The bill did not get out of committee.

Ms. Ayala, who was elected in November with the help of more than $1 million from Mr. Soros, did not campaign on a platform of ending the death penalty, causing some to accuse her of masking her intentions. In response, Ms. Ayala has pointed out that executions in Florida were suspended until recently because of court challenges. In a court motion, Ms. Ayala said she took office intending to pursue the death penalty if it were reinstated, but changed her mind after “careful, intensive and individualized consideration” of the Loyd case.

I think we are entering a time where people want accountable and smart people in power,” Ms. Ayala said in an interview. “They want someone who isn’t just emotionally based or ‘This is the way we always have done it.’ But, ‘Is this smart? Is this reducing crime?’”

Joshua Marquis, a district attorney in Oregon and a board member of the National District Attorneys Association, said if he opposed the death penalty, he would not have run for office. Ms. Ayala has substituted her judgment for the law, added Mr. Marquis, a Democrat.

Jeffrey L. Ashton, the incumbent whom Ms. Ayala defeated in the Democratic primary last year, agreed. “That’s not a prosecutor’s job to decide which law they’ll follow and which they won’t,” he said. “I think it’s illegal, honestly.”

The morning after Ms. Ayala’s announcement, dozens of clergy, activists and families of murder victims flocked to the steps outside her Orlando office to both praise and criticize her. One of the Pulse nightclub victims showed up in a wheelchair calling for an eye for an eye, even as the mothers of three murder victims took Ms. Ayala’s side.

As the clergy members spoke out in her favor, Rafael Zaldivar photo-bombed their news conference with a poster of his murdered son, Alex, killed in 2012 by a man against whom he was to testify in a home invasion case.

“I was stunned to hear what she had to say,” Mr. Zaldivar said.“She is taking up a political agenda from the far left.” He argued that the election had been “bought” by Mr. Soros.

But Ms. Ayala’s supporters say that conservative organizations have donated to prosecutors’ races for decades. Ms. Ayala insisted that she had never met Mr. Soros, and that nobody from his team had discussed the death penalty with her during the race. “It’s not a quid pro quo where I owe him something,” she said.

Mr. Soros and his representatives declined to be interviewed for this article.

The mother of Mr. Loyd’s ex-girlfriend said she supported Ms. Ayala’s decision.

“When it comes to death penalty, you have to understand that we want is closure,” said Stephanie Dixon-Daniels, whose daughter Sade Dixon, 24, was murdered in December. “He’s not going to be executed for another 30, 40 years anyway.”