Everything you need to know about Ron DeSantis 4:31

(CNN) -- Florida Gov. Ron DeSantis, now officially running for president, is no longer tiptoeing around when it comes to former President Donald Trump, nor is he being coy about his plans to push the limits of the presidency's powers like never before if he wins the White House.

DeSantis — whose campaign raised $8.2 million in the first 24 hours, according to a spokesman — filled the hours after his bumpy campaign launch on Twitter by taking his message to the familiar comforts of conservative airwaves where, in a dozen interviews, he has attacked Trump as fiscally irresponsible and a supporter of amnesty for undocumented immigrants. DeSantis said mitigation policies from the covid-19 era when Trump was in power "destroyed the lives of millions of people." He also told Fox News that his "day one" priority would be to fire former President Christopher Wray's handpicked FBI director.

Trump "is a different guy today than he was when he was running in 2015 and 2016," DeSantis told conservative Tennessee broadcaster Matt Murphy, adding, "I don't know what happened to Donald Trump."

The sharpening of attacks on Trump — whose endorsement DeSantis once sought and campaigned for in his 2018 gubernatorial race — comes after months of subtle hints at the former president's time in the White House. Throughout Trump's four years in office — of which DeSantis served nearly two years in Congress and two years as a closely aligned governor — and in the years since, the Florida Republican has never before issued such direct and public criticism of the man he now hopes to supplant as GOP leader.

Now DeSantis is arguing that he is best suited to deliver on promises that Trump himself failed to keep.

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That will require pushing the limits of the executive branch like never before, DeSantis has suggested in multiple interviews over the past 24 hours. He told conservative radio host Mark Levin that he had studied the "leverage points" of the U.S. Constitution and would use his knowledge to exercise the "true scope" of presidential power.

"You have to know how to use your influence to advance what you're trying to accomplish," DeSantis told Twitter CEO Elon Musk during their conversation on the day of his presidential bid launch.

Trump has countered these missives by mocking the rulings that marred the Florida Republican's entry into the race and suggesting that DeSantis is not prepared for the Oval Office.

"'Rob' DeSanctimonious and his poll numbers are falling like a rock. I'd almost be inclined to say they're record drops," Trump posted on Truth Social on Thursday. "The question is whether Rob is young, inexperienced and naïve or, more worryingly, whether he is a fool who has no idea what he is doing. We already have one of those in office, we don't need another. We need MAGA."

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DeSantis and the Republican Party

DeSantis' vision for executive power is apparently at odds with the GOP's traditional adherence to the principles of government with limits. Many Republicans often accused former President Barack Obama of unconstitutionally extending his powers, and DeSantis himself wrote an entire book in 2011 based on that perception. But it's an approach Republican voters have come to expect from their elected leaders in the years since Trump emerged and dispensed with rules of government.

It's also in keeping with the way DeSantis has led from Tallahassee. As governor, DeSantis has systematically strengthened the governor's office and stretched his constitutional powers in a way that no previous executive has done. He took control of the state environmental protection agency, deployed the state's police force in novel ways, created a law enforcement team to oversee voting, removed a democratically elected local prosecutor, and orchestrated the acquisition of a small liberal arts college.

DeSantis has treated state bureaucracies that once operated independently as extensions of his executive offices. He has supplied state regulatory boards with like-minded political appointees, who have followed suit in banning gender-affirming care for minors and expanding restrictions on school lessons on sexual orientation and gender identity. He has punished Disney, the state's tourism engine and its flagship company, for defying him with those restrictions, and forced state lawmakers to approve a new congressional map drawn up by his office.

"I may have gotten 51 percent of the vote, but that entitles me to exercise 100 percent executive power, and I've decided to use it to advance conservative principles," DeSantis said at a rally in Wisconsin on May 6.

In his latest book, "The Courage to Be Free," DeSantis described his extraordinary use of state power as deliberate and tactical. He wrote that before taking office he had studied an "exhaustive list" of the governor's constitutional authority and would use "every lever available to advance our priorities."

"What I was able to bring to the governor's office was an understanding of how a constitutional form of government works, the various pressure points that exist, and how best to leverage authority to achieve substantive political victories," he wrote.

Now, DeSantis' initial message to Republican voters is that he would bring that methodical precision to the White House in a way that previous executives — Trump included — failed to.

"Presidents have been unwilling to wield the power of Article Two to discipline the bureaucracy," DeSantis said.

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DeSantis' promises if he becomes president

Among his top priorities, DeSantis said, would be "reconstitutionalizing" the federal government, something he described as a plan to "discipline the bureaucracy" and agencies he said are "detached from constitutional responsibility."

It would end the long-standing tradition of government institutions like the U.S. Department of Justice operating independently of the president, adopting a philosophy that Trump usually governs with, but has never articulated so succinctly.

"Republican presidents have accepted the lie that the Justice Department and the FBI are, quote-unquote, independent," DeSantis said. "They are not independent agencies. They are part of the executive branch. They answer to the president-elect of the United States."

DeSantis also touched on the issue of pardons when asked about whether he would consider the cases of those facing charges related to the Jan. 6, 2021, insurrection at the U.S. Capitol, as well as whether he would pardon Trump should he be federally impeached.

It said it would examine all cases of "unfavourable treatment based on politics or militarization".

At the same time, DeSantis said pardons would be considered individually, not necessarily an entire group.

"We're going to apply relief as appropriate," DeSantis said. "It will be done on a case-by-case basis."

Those remarks drew immediate rebuke from the Democratic Party, warning in a press release that DeSantis was "spending his first day as an official presidential candidate promising to consider pardons for some Jan. 6 insurgents and convicted criminals who attacked law enforcement."

In his private address to donors, Desantis has pointed to the fact that Trump cannot then seek another term if elected. Since launching his candidacy Wednesday, DeSantis has more publicly laid out why that should give Republicans pause.

"I understand, and all your listeners should understand," DeSantis said on Levin's show, "that if we do everything right, if we're disciplined, if we're as strong as anybody could be, you still need a two-term project."

-- CNN's Jeff Simon and Kate Sullivan contributed to this report.

Ron DeSantis