Corey Lewandowski, seen here talking with reporters in New York in May, was fired Monday as presumptive Republican presidential nominee Donald Trump’s campaign manager. (Spencer Platt)

Donald Trump abruptly fired top aide Corey Lewandowski on Monday in an urgent move to reboot his floundering general-election campaign, which has been besieged by organizational turmoil, strategic mishaps and an erratic message.

Trump’s dismissal of Lewandowski — his combative campaign manager and one of his longest-serving aides — was seen as an effort to calm allies, donors and Republican officials who have grown increasingly alarmed by recent missteps and unwanted dramas that threaten to undermine the presumptive GOP presidential nominee’s chances in November.

A Trump loyalist whose mantra was “Let Trump be Trump,” ­Lewandowski chafed at suggestions that the candidate behave more presidentially. His departure consolidates power around veteran GOP operative and lobbyist Paul Manafort, Trump’s campaign chairman and senior strategist, who has been trying with limited success to professionalize the campaign.

Lewandowski’s internal turf battles with Manafort were intense and at times paralyzed the campaign. The manager’s relations with senior staff at the Republican National Committee had so deteriorated that RNC Chairman Reince Priebus implored Trump to make a change, according to two Republicans briefed on the matter who requested anonymity to speak candidly.

Lewandowski also ran afoul of Trump’s family, especially his daughter Ivanka and her husband, Jared Kushner, who convinced Trump he needed a centralized management structure for the general election, according to people briefed on the decision. Trump fired Lewandowski at a meeting Monday morning that was attended by the candidate’s adult children, one of those people confirmed.

Presumptive Republican nominee Donald Trump fired embattled campaign manager Corey Lewandowski on June 20. The Fix's Chris Cillizza breaks down what comes next. (The Washington Post)

Lewandowski was escorted from Trump Tower flanked by security guards.

The campaign he leaves behind faces immediate challenges: The fundraising operation is sputtering; the ground game in battleground states is shockingly thin; key jobs at the national headquarters in New York have gone unfilled for months; the campaign has not aired a single television advertisement to counter Democrat Hillary Clinton’s swing-state ad blitz; and aides struggle to coordinate strategy and basic operational tasks with the RNC.

Monthly fundraising totals released Monday night underscored Trump’s difficulties. In May, his campaign reported raising $3.1 million and entered June with $1.3 million on hand — a meager total akin to a House candidate’s. That puts him at a severe disadvantage against Clinton, who raised $28 million in May and ended the month with $42 million on hand.

Former House speaker Newt Gingrich, a Trump supporter who is considered a possible running mate, said Trump and his team are “rapidly learning the general election, 50 states simultaneously, is a much bigger, more complex system.”

Gingrich praised Lewandowski for what he described as a historic primary campaign. But Gingrich said in an interview, “The general election is like a gigantic football team — it takes a whole different set of requirements both for the candidate and for the team.”

It remains to be seen whether Lewandowski’s ouster is the beginning of a general-election pivot by the candidate or by his political operation. Supporters, including New Jersey Gov. Chris Christie (R), have been privately urging a change to avert what they fear could be certain defeat on Election Day.

In the seven weeks since he secured the delegates to claim the GOP nomination, Trump has rejected calls to develop a more inclusive and disciplined message. Instead, he has relished distracting feuds, one after another, which appear to have contributed to his decline in public polls.

Some leading Republicans were doubtful the staff shake-up would have a meaningful effect on the campaign’s trajectory, which they see as strongly favoring Clinton, the presumptive Democratic nominee. GOP leaders are concerned that Trump’s incendiary rhetoric could doom the party at large, endangering the Republican Senate and House majorities.

“The problem is Trump,” said veteran Republican strategist Mike Murphy, a Trump critic. “You can fire all the yes men you want, but the campaign reflects on the candidate, and the candidate is hopelessly flawed.”

John Weaver, another GOP strategist and Trump critic, said: “Corey’s core message was that he was allowing Trump to be Trump. So my question is, now that Corey is gone, will Trump stop being Trump? That’s the only way to fix this.”

Lewandowski told CNN on Monday that he did not know why he was fired.

“I think in all campaigns you have detractors and you have supporters. That’s the nature of the beast,” he said. He painted a rosy portrait of the campaign, denied there were internal skirmishes, and refused to criticize Trump or rivals in the campaign.

In March, Trump repeatedly defended Lewandowski against charges that he had assaulted a reporter at a news conference in Florida. But despite his earlier loyalty, Trump let his top aide go.

In a statement released Monday, campaign spokeswoman Hope Hicks said: “The Donald J. Trump Campaign for President, which has set a historic record in the Republican Primary having received almost 14 million votes, has today announced that Corey Lewandowski will no longer be working with the campaign. The campaign is grateful to Corey for his hard work and dedication and we wish him the best in the future.”

Trump praised Lewandowski in a Fox News interview that aired Monday night, calling him “a good man” and “a talented person.” Explaining his decision, Trump said: “We’re going to go a little bit of a different route from this point forward. A little different style.”

Lewandowski was not the only senior aide to leave the campaign. Michael Caputo, a communications and political adviser, resigned Monday afternoon after sending a tweet mocking Lewandowski with a “Wizard of Oz” reference: “Ding dong the witch is dead!” The tweet, Caputo wrote in his resignation letter, “was too exuberant a reaction to this personnel move.”

The campaign sought to project an image of competence Monday after Lewandowski’s ouster, which many staffers first heard about through news reports. Manafort led a staff-wide phone call in which he complimented Lewandowski’s work and said the campaign would expand its ranks in the coming weeks, according to people on the call.

Trump held a private strategy meeting with family members and senior advisers, which was described as “upbeat” and “very forward-looking” by one person briefed on the session. The team discussed plans for the mid-July Republican National Convention in Cleveland, the selection of a vice-presidential running mate and fundraising. They also mapped out paths to victory in key battleground states and crafted a message tightly tailored to the economy and national security, said this person, who demanded anonymity to discuss internal matters.

The Trump team faces an immediate test Tuesday and Wednesday with a series of New York fundraising events. Steven Mnuchin, Trump’s national finance chairman, has been scrambling to get commitments from major GOP donors. One fundraiser involved in the effort said it was “a question mark” whether the events would be successful.

One of Trump’s first campaign hires, Lewandowski was an architect of his successful strategy, based on extensive media attention and massive rallies, throughout the primaries. Lewandowski became a force of personality, building a loyal stable of lieutenants at Trump Tower in New York and in states across the country.

He became known for his short temper and would explode at staff members and reporters who challenged or angered him — something he would brag about as a strength. Over the course of the campaign, Lewandowski repeatedly was caught saying things that were untrue, although he seemed to face no public repercussions for doing so.

In March, conservative reporter Michelle Fields accused Lewandowski of roughly grabbing her arm after a news conference at one of Trump’s golf courses in Florida. Lewandowski denied having touched Fields and tweeted that she was “totally delusional,” but video from Trump’s security cameras, later released by Florida authorities, showed Lewandowski grabbing Fields.

Lewandowski lost the trust of Trump’s three adult children involved in the campaign — Donald Jr., Ivanka and Eric — when they learned he had been pitching reporters to write negative stories about Kushner, Ivanka’s husband, who had emerged as a rival adviser, according to a Republican briefed on the episode.

Lewandowski came under scrutiny for the campaign’s connection to a pro-Trump super PAC run last year by Mike Ciletti, a Colorado Republican operative who worked closely with Lewandowski in previous jobs. Lewandowski initially told The Washington Post that he did not know Ciletti, then was forced to admit they were longtime associates. In the wake of The Post’s reporting, Ciletti shuttered the super PAC last fall.

After that, the Trump campaign began directing large sums to a printing company, WizBang Solutions, where Ciletti serves as a director. In all, the campaign paid WizBang more than $2 million for printing, design and telemarketing through the end of April, making the company the campaign’s fourth-largest vendor.

Trump himself has been under heavy fire in recent weeks for a string of damaging controversies — from his clumsy response to the mass shooting in Orlando that included unfounded accusations against American Muslims to his highly personal attacks against a federal judge overseeing two lawsuits against him to his campaign’s failure to disburse pledged donations for veterans’ charities.

Just as alarming to Trump’s supporters is his failure so far to build a national infrastructure and fundraising apparatus in the same league as Clinton’s. Trump heard these worries firsthand last week as he embarked on a cross-country fundraising trip.

Mica Mosbacher, a longtime Republican fundraiser who helped Trump and the RNC arrange donor events in Texas, said that “you need seasoned operatives” running a general-election campaign.

“Corey did a good job,” she said, but added, “I would not call him a seasoned operative.”

Former Oklahoma governor Frank Keating echoed the sentiments of many Republican establishment figures when he said Trump needs to show how he would govern.

“Donald Trump may be a billionaire businessman,” Keating said. “But the question is, will he be a trillionaire political and governmental leader? Switching your campaign manager, if that will bring some stability, that’s all good. But all of us who love our party and our country want to see specifics from him as to what he’s going to do, when and why.”

Matea Gold and Jenna Johnson contributed to this report.