The evolution of the Republican Party under the influence of former President Donald J. Trump calls into question a post-Watergate norm.Donald J. Trump has promised that if he wins back the presidency he will appoint a special prosecutor to “go after” President Biden and his family.But he’s not the only Republican running for president who appears to be abandoning a long-established norm in Washington — presidents keeping their hands out of specific Justice Department investigations and prosecutions.Mr. Trump, who leads the G.O.P. field by around 30 percentage points in public national polls, wields such powerful influence that only a few of his Republican rivals are willing to clearly say presidents should not interfere in such Justice Department decisions.After Mr. Trump’s vow to direct the Justice Department to appoint a “real” prosecutor to investigate the Bidens, The New York Times asked each of his Republican rivals questions aimed at laying out what limits, if any, they believed presidents must or should respect when it comes to White House interference with federal law enforcement decisions.Their responses reveal a party that has turned so hard against federal law enforcement that it is no longer widely considered good politics to clearly answer in the negative a question that was once uncontroversial: Do you believe presidents should get involved in the investigations and prosecutions of individuals?Mr. Trump’s closest rival, Gov. Ron DeSantis of Florida, has flatly said he does not believe the Justice Department is independent from the White House as a matter of law, while leaving it ambiguous where he stands on the issue of presidents getting involved in investigation decisions.Mr. DeSantis’s spokesman, Bryan Griffin, wrote in an email that comments the governor made on a recent policy call “should be instructive to your reporting.”Gov. Ron DeSantis of Florida said the president can lawfully exert more direct control over the Justice Department and F.B.I. than has traditionally been the case.Jason Henry for The New York TimesIn the comments, Mr. DeSantis says that “the fundamental insight” he gleans from the Constitution is that the Justice Department and F.B.I. are not “independent” from the White House and that the president can lawfully exert more direct control over them than traditionally has been the case.“I think presidents have bought into this canard that they’re independent, and that’s one of the reasons why they’ve accumulated so much power over the years,” Mr. DeSantis said. “We will use the lawful authority that we have.”But the context of Mr. DeSantis’s remarks was mostly about a president firing political appointees and bureaucrats at the Justice Department and the F.B.I., not about a president ordering them to target specific people with investigations and prosecutions. Mr. Griffin did not respond when asked in a follow-up on this point.Mr. Trump has portrayed his legal troubles as stemming from politicization, although there is no evidence Mr. Biden directed Attorney General Merrick Garland to investigate Mr. Trump. Under Mr. Garland, Trump-appointed prosecutors are already investigating Mr. Biden’s handling of classified documents and on Tuesday secured a guilty plea from Mr. Biden’s son, Hunter, on tax charges.Especially since Watergate, there has been an institutional tradition of Justice Department independence from White House control. The idea is that while a president can set broad policies — directing the Justice Department to put greater resources and emphasis on particular types of crimes, for example — he or she should not get involved in specific criminal case decisions except in rare cases affecting foreign policy.This is particularly seen as true for cases involving a president’s personal or political interests, such as an investigation into himself or his political opponents.But even in his first term, Mr. Trump increasingly pressed against that notion.William P. Barr, left, Mr. Trump’s attorney general, refused Mr. Trump’s baseless demand that he say the 2020 election had been corrupt.Anna Moneymaker for The New York TimesIn the spring of 2018, Mr. Trump told his White House counsel, Donald F. McGahn II, that he wanted to order the Justice Department to investigate his 2016 rival, Hillary Clinton, and James B. Comey Jr., the former head of the F.B.I. Mr. McGahn rebuffed him, saying the president had no authority to order an investigation, according to two people familiar with the conversation.Later in 2018, Mr. Trump publicly demanded that the Justice Department open an investigation into officials involved in the Russia investigation. The following year, Attorney General William P. Barr indeed assigned a Trump-appointed U.S. attorney, John Durham, to investigate the investigators — styling it as an administrative review because there was no factual predicate to open a formal criminal investigation.Mr. Trump also said in 2018 and 2019 that John F. Kerry, the Obama-era secretary of state, should be prosecuted for illegally interfering with American diplomacy by seeking to preserve a nuclear accord with Iran. Geoffrey S. Berman, a former U.S. attorney in Manhattan whom Mr. Trump fired in 2020, later wrote in his memoir that the Trump Justice Department pressured him to find a way to charge Mr. Kerry, but he closed the investigation after about a year without bringing any charges.And as the 2020 election neared, Mr. Trump pressured Mr. Barr and Mr. Durham to file charges against high-level former officials even though the prosecutor had not found a factual basis to justify any. In his own memoir, Mr. Barr wrote that the Durham investigation’s “failure to deliver scalps in time for the election” eroded their relationship even before Mr. Barr refused Mr. Trump’s baseless demand that he say the 2020 election had been corrupt.Where Mr. Trump’s first-term efforts were scattered and haphazard, key allies — including Jeffrey B. Clark, a former Justice Department official who helped Mr. Trump try to overturn the 2020 election — have been developing a blueprint to make the department in any second Trump term more systematically subject to direct White House control.Against that backdrop, Vivek Ramaswamy, one of the long-shot G.O.P. challengers, has pledged to pardon Mr. Trump if Mr. Ramaswamy wins the presidency. He said that as a constitutional matter, he thinks a president does have the power to direct prosecutors to open or close specific criminal investigations. But he added that “the president must exercise this judgment with prudence in a manner that respects the rule of law in the country.”Vivek Ramaswamy said he would respect the post-Watergate norm regarding Justice Department independence.Jordan Gale for The New York TimesAsked if he would pledge, regardless of his views on what the law may technically allow presidents to do, to obey the post-Watergate norm, Mr. Ramaswamy replied: “As a general norm, yes.”Two Republican candidates who are both former U.S. attorneys unequivocally stated that presidents should not direct the investigations or prosecutions of individuals. Tellingly, both are chasing votes from anti-Trump moderate Republicans.Chris Christie, a former New Jersey governor who was a U.S. attorney in the George W. Bush administration, said he knew “just how important it is to keep prosecutors independent and let them do their jobs.”“No president should be meddling in Department of Justice investigations or cases in any way,” Mr. Christie added. “The best way to keep that from happening is with a strong attorney general who can lead without fear or favor.”And Asa Hutchinson, a former Arkansas governor and congressman who served as a U.S. attorney in the Reagan administration, said that “preserving an independent and politically impartial Department of Justice in terms of specific investigations is essential for the rule of law and paramount in rebuilding trust with the American people.”A spokesman for former Vice President Mike Pence, Devin O’Malley, was terse. He said a president could remove senior law enforcement officials and expressed some support for Justice Department independence. But he declined to add further comment when pressed.“Mike Pence believes that the president of the United States has the ability to hire and fire the attorney general, the F.B.I. director, and other D.O.J. officials — and has, in fact, pledged to do so if elected — but also believes the D.O.J. has a certain level of independence with regard to prosecutorial matters,” Mr. O’Malley said.Mr. Trump’s former vice president, Mike Pence, through a spokesman, expressed some support for Justice Department independence.John Tully for The New York TimesMost other candidates running against Mr. Trump landed in what they apparently deemed to be a politically safer space of blending general comments about how justice should be administered impartially with vague accusations that the Biden-era Justice Department had targeted Republicans for political reasons.Many did not specifically point to a basis for those accusations. Among a broad swath of conservatives, it is taken as a given that the F.B.I. and Justice Department must be politically motivated against them on a variety of fronts, including the scrutiny over the 2016 Trump campaign’s links to Russia, the prosecution of people who rioted at the Capitol on Jan. 6, 2021, and the Trump documents case.Matt Gorman, a senior communications adviser for Senator Tim Scott of South Carolina, declined to say whether or not Mr. Scott believed presidents should interfere in specific investigations. He pointed only to Mr. Scott’s comments on the most recent “Fox News Sunday” appearance.In those remarks, Mr. Scott said: “We have to clean out the political appointments in the Department of Justice to restore confidence and integrity in the D.O.J. Today, we want to know that in our justice system, Lady Justice wears a blindfold and that all Americans will be treated fairly by Lady Justice. But today, this D.O.J. continues to hunt Republicans while they protect Democrats.”Nikki Haley, the former United Nations ambassador, also provided an ambiguous answer through her spokeswoman, Chaney Denton. She pointed to two specific conservative grievances with law enforcement: Seven years ago, Hillary Clinton was not charged over using a private email server while secretary of state, and the Trump-era special counsel, Mr. Durham, wrote a report this year criticizing the Russia inquiry.“The Department of Justice should be impartial, but unfortunately it is not today,” Ms. Denton said. “The Durham Report, the non-prosecution of Hillary Clinton, and other actions make it clear that a partisan double standard is being applied. The answer is not to have both parties weaponize the Justice Department; it’s to have neither side do it.”“The Department of Justice should be impartial,” a spokeswoman for Nikki Haley said, without getting into specifics.Haiyun Jiang/The New York TimesWhen specifically pressed, Ms. Denton declined to say whether Ms. Haley believes presidents should get involved in prosecutions or investigations of individuals.One recent entrant to the race, Mayor Francis X. Suarez of Miami, disavowed the post-Watergate norm, putting forward a premise that law enforcement officials are currently politically biased and so his White House interference would be to correct that purported state of affairs.“I certainly would not promise that I would allow a biased department operate independently,” he said in part of a statement. “I believe it is the president’s responsibility to insist that justice is delivered fairly without bias or political influence.”A spokesman for Gov. Doug Burgum of North Dakota, Lance Trover, was even more vague.“Gov. Burgum believes that citizens’ faith in our institutions is the foundation of a free and just society and will not allow them to be a political enforcement extension of the party in power as we have seen in failed countries,” he said. “If Americans have distrust in the Justice Department when he takes office, he will do what it takes to restore the American people’s faith in the Department of Justice and other bedrocks of our democracy.” More