Ron DeSantis’s long-awaited official entry into the 2024 presidential campaign went haywire at its start on Wednesday during a glitch-filled livestream over Twitter.Despite the problems, Mr. DeSantis, the combative 44-year-old Republican governor of Florida who has championed conservative causes and thrown a yearslong flurry of punches at America’s left, provides Donald J. Trump the most formidable Republican rival he has faced since his ascent in 2016. His candidacy comes at a pivotal moment for the Republican Party, which must choose between aligning once more behind Mr. Trump — who lost in 2020 and continues to rage falsely about a stolen election — or uniting around a new challenger to take on President Biden.But on Wednesday, Mr. DeSantis’s official run for the White House got off to an embarrassing start as the planned livestream with Twitter’s eccentric billionaire owner, Elon Musk, was marred by technical problems and dead air. The audio cut in and out amid talk of “melting the servers,” hot mic whispering and on-the-spot troubleshooting.When, after more than 25 minutes, Mr. DeSantis finally spoke, he declared, “I am running for president of the United States to lead our great American comeback.”The extended social media hiccup — as more than 500,000 people were waiting — was gleefully cheered on the very platform Mr. DeSantis was supposed to be commandeering for his campaign. Donald Trump Jr. wrote a single word: “#DeSaster.” Mr. Biden posted a donation button to his re-election campaign with the words, “This link works.” The audience when Mr. DeSantis did deliver his remarks was smaller than it had been during the initial minutes when no one was speaking.Despite his inauspicious start on Wednesday and having slipped well behind Mr. Trump in polls in recent months, Mr. DeSantis retains a host of strengths: a mountain of cash, a robust campaign operation and a series of conservative policy victories in Florida after a landslide re-election triumph last fall. The governor, who rose to national prominence with his restriction-averse handling of the coronavirus pandemic, argues that his “Florida Blueprint” can be a model for reshaping the United States in a starkly conservative mold, especially on social issues.“American decline is not inevitable,” Mr. DeSantis said. “It is a choice. And we should choose a new direction, a path that will lead to American revitalization.” He accused Mr. Biden of taking “his cues from the woke mob.”Mr. DeSantis did not mention Mr. Trump by name. But he did sketch out some of the contrasts he is expected to sharpen in the coming months. “We must look forward, not backwards,” he said on the Twitter Space livestream. “We need the courage to lead and we must have the strength to win.”The DeSantis campaign had invited prominent donors to Miami on Wednesday for a fund-raising event, hosting them at a conference space at the Four Seasons as the Twitter discussion was projected onto a large screen. Then they waited. And waited.“Elon’s got to staff up a little more to boost that server capacity,” said Brandon Rosner, a donor from Milwaukee. He was not discouraged. “Once we got through the original glitch there, I think people were very excited,” he said.Mr. DeSantis is confronting the daunting endeavor of toppling a former president whose belligerence and loyal base of support have discouraged most leading Republicans from making frontal attacks against him. Mr. Trump, who has a mounting list of legal troubles, clearly sees Mr. DeSantis as a political threat and has unloaded on him for months, mocking him as “Ron DeSanctimonious” and slamming his stewardship of Florida.“Trump is not as invincible as he once seemed and DeSantis is a serious contender,” said Mike Murphy, a veteran Republican strategist. “There are Republican voters looking for someone who can move beyond Trump, someone who can fight the liberals but also win elections. That’s the space DeSantis is trying to inhabit.”Mr. DeSantis’s chances of capturing the nomination may depend on whether the Republican primary becomes a crowded, Trump-dominated food fight — something similar to what unfolded in 2016 — or if he can turn the contest into a two-man race. The Republican field has slowly ballooned, with Senator Tim Scott of South Carolina announcing a bid this week and Vice President Mike Pence expected to join soon.To winnow the field back down, Mr. DeSantis is likely to need strong showings in Iowa and New Hampshire, the first two nominating states, with anti-Trump voters coalescing around him. His advisers and allies see a victory in socially conservative Iowa as a must, and believe he needs to follow with at least a close second-place finish in more moderate New Hampshire.Mr. DeSantis has the financial ammunition to compete: He is likely to start with more money in an outside group than any Republican primary candidate in history. He has more than $80 million expected to be transferred from his state account to his super PAC, which says it has also raised $40 million, in addition to having tens of millions more in donor commitments, according to people familiar with the fund-raising.A key focus of the primary, and the general election should Mr. DeSantis make it that far, will be his record as governor. He and a pliant Florida Legislature have passed contentious laws that have excited the right and angered many Democrats, including Black and L.G.B.T.Q. people, students and abortion-rights supporters in Florida. The bills seem to reflect Mr. DeSantis’s plan to run to the right of Mr. Trump in the primary, which could leave him vulnerable with moderates and independents.In the most recent legislative session alone, Florida Republicans banned abortion after six weeks of pregnancy; expanded the use of the death penalty; allowed Floridians to carry concealed guns without a permit; restricted gender-transition care for minors; limited teaching about gender identity and sexual orientation; defunded diversity, equity and inclusion programs at public colleges; and shielded records of his own scrutinized travel from the public.Mr. DeSantis has also shown a willingness to use executive power in ways little seen before in Tallahassee, the state capital, leading some Democrats and civil rights leaders to worry that he shares Mr. Trump’s strongman style but has a greater ability to carry out that vision.He has picked a long-running fight with Disney, one of Florida’s largest employers and a canny political adversary. He removed a local prosecutor from office in what records show was a decision motivated by politics, installed his allies at a public liberal arts university in a bid to transform it into a bastion of conservative thought, said he would reject a high school Advanced Placement course on African American studies for “indoctrinating” students and had state law enforcement officers monitor holiday drag shows for lewd behavior.While his stump speech focuses on a lengthy recounting of those and other conservative policy achievements, Mr. DeSantis is expected to start talking more about his biography, with help from his wife, Casey DeSantis, a former television journalist who plays an influential role in his office and decision-making.Raised in Dunedin, a suburb of Tampa, Mr. DeSantis grew up in a working-class home. He excelled at baseball, captaining the squad at Yale University as a hard-hitting outfielder.He later enrolled at Harvard Law School, then served in the Navy as a military lawyer, deploying to Guantánamo Bay and Iraq. He worked as a federal prosecutor in Florida before winning election to Congress in 2012. He was a founding member of the House Freedom Caucus, a group of anti-establishment conservatives.After three terms in Washington, he ran for Florida’s open governorship, winning the Republican primary largely thanks to an endorsement from Mr. Trump. But they fell out when Mr. DeSantis began making noises about running for president in 2024.The pandemic turned Mr. DeSantis into a Fox News fixture. He has criticized social distancing measures, masks and vaccines — tools fitfully employed by the Trump administration — and has already hinted that he will contrast his actions in Florida with Mr. Trump’s approach. In particular, Mr. DeSantis has gone after Dr. Anthony S. Fauci, who led the nation’s pandemic response.But the step-up from a statewide campaign, even one as successful as Mr. DeSantis’s nearly 20-percentage-point romp, to a presidential campaign is not easy. As the initial Twitter Space floundered on Wednesday, Mr. Musk was forced to post a new link, severely reducing the audience for Mr. DeSantis’s announcement.While more than 500,000 people tuned in to the first Twitter Space, the second one had only 163,000 listeners by the time Mr. Musk and the technology entrepreneur David Sacks began interviewing the governor. The conversation quickly turned into a surprisingly dry discussion about the overreach of federal agencies, the merits of Twitter and occasionally bizarre tangents like the license plate number of Representative Thomas Massie, a Kentucky Republican who has endorsed Mr. DeSantis and joined the online conversation.Mr. DeSantis’s campaign tried to put a positive spin on the technical mishaps, writing on Twitter: “It seems we broke the internet with so much excitement.” An aide announced they had raised $1 million in an hour. All the while, Mr. Trump’s team rejoiced. “This is criminal for a campaign,” said Chris LaCivita, a senior adviser to the former president.Mr. DeSantis had waited months to declare his candidacy, citing a need for Florida’s Legislature to first complete its session in early May. The delay allowed Mr. Trump to test out attacks on Mr. DeSantis and secure the endorsement of numerous members of Congress, including several from Florida.As Mr. DeSantis ramped up his presidential preparations this year with a book tour and a trip abroad, he has seemed to struggle at points.Awkward moments — including cringeworthy facial expressions — generated negative headlines. So did some poorly calculated policy pronouncements, particularly his declaration that defending Ukraine from the Russian invasion was not a vital U.S. interest. Some major donors who once saw him as the most suitable Trump challenger backed away.At the heart of the criticism is the perception that Mr. DeSantis, a supreme believer in his own abilities, can seem aloof and quick to anger. Even his allies acknowledge he is not the backslapping, baby-kissing type — concerns he has tried to address by spending more time greeting voters and taking selfies.“He is an introvert in an extrovert’s job,” said Alex Andrade, a Republican state representative from the Florida Panhandle who says he admires the governor’s reserved and analytical approach.In recent weeks, Mr. DeSantis has seemed to recover from his wobbles, hitting back with more force against Mr. Trump. He has criticized the former president for not endorsing Florida’s six-week abortion ban and has described a “culture of losing” overtaking the Republican Party under Mr. Trump. He also told donors in a private call that Mr. Trump could not beat Mr. Biden.In the Twitter event, Mr. DeSantis took some sideswipes at the former president, a onetime reality television star, at one point saying, “Government is not entertainment. It’s not about building a brand or virtue-signaling.”As they wrapped up the hourlong conversation, which meandered from Article 2 of the Constitution to Bitcoin, Mr. DeSantis said, “We should do it again. I mean, I think it was fun.”Mr. Sacks concurred. “It’s not how you start,” he added, “it’s how you finish.”Jonathan Swan More