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 professionalise the campaign.
Michael Caputo, who was poised to serve as director of communications for the campaign at the GOP convention, later resigned after firing off a celebratory tweet following word of Lewandowski's dismissal.
He tweeted, "Ding dong the witch is dead!" Accompanying the tweet was a photo from the Wizard of Oz, showing the feet of the Wicked Witch of the East protruding from under a house.
Efforts to unite the party around Trump will not have been helped by the Free The Delegates campaign. Organisers concede their plan could worsen internal party strife but they believe that they are responding to deep-rooted concerns among conservatives about Trump.
"Short-term, yes, there's going to be chaos," said Kendal Unruh, a co-founder of the group. "Long-term this saves the party and we win the election. Everything has to go through birthing pains to birth something great. We're going to go through the trauma of the birthing pains, but the reward will be worth it." Unruh said her cause is winning support from "the non-rabble-rousers; the rule-following, church-going grandmas who aren't out protesting in the streets". "This is the way they push back." Unruh and other GOP delegates from Colorado hatched the idea of trying to stop Trump by introducing a rule change: Instead of binding delegates to the results of the caucuses and conventions - as many party leaders insist they are - the convention's 2472 delegates should instead be able to vote their conscience and select whomever they want.
For weeks, Unruh, her colleague Regina Thomson and other Colorado Republicans sought out like-minded delegates in other states. After Unruh appeared in newspaper interviews and called in to a few radio talk shows, she said other delegates with similar concerns in places like Louisiana and Missouri reached out. By the weekend, Unruh was consulting a lawyer about possible fundraising plans while Thomson was compiling the list of interested delegates, building a website and booking a conference call phone line that could host 1000 participants.
Thomson said that at least 1000 people participated in the call. Delegates who participated said they plan to spend this week wooing others to the cause.
"Trump claims to be pro-life, but he used to be pro-abortion. He claims to be for traditional marriage, but he never used to talk that way. His lifestyle is such that I cannot support him," said Gayle Ruzicka of the conservative group Eagle Forum.
In recent days Trump has called attempts to strip him of the party nomination "totally illegal" and a rebuke of the millions of people who voted for him. Over the weekend he accused former opponents Jeb Bush and Texas Senator Ted Cruz of trying to undermine his candidacy. Both men say they have nothing to do with the new movement.
On Monday, leaders of Free the Delegates repeatedly insisted that they are not working on behalf of any of Trump's former opponents.
Meanwhile, Lewandowski was escorted from Trump Tower flanked by security guards.
The campaign he leaves behind faces challenges beyond the Free The Delegates movement: 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.
Trump supporters, including New Jersey Governor Chris Christie, 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 evolve into sending 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 favouring Clinton, the presumptive Democratic nominee. 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."
No plea over plan to kill
A British man arrested at a weekend Donald Trump rally in Las Vegas tried to grab a police officer's gun so he could kill the presidential candidate after planning an assassination for about a year, according to authorities.
US Secret Service agents said Michael Steven Sandford approached a Las Vegas police officer at the campaign stop to say he wanted Trump's autograph, but then tried to take the weapon.
A complaint filed yesterday in the US District Court in Nevada charges Sandford, 20, with an act of violence on restricted grounds. He was denied bail. His court-appointed attorney said he was living out of his car and in the country illegally.
Sanford has not entered a plea.
Sandford's assigned public defender, Heather Fraley, said Sandford appeared to be competent. She said he hadn't been diagnosed with a mental illness but that he has autism and previously attempted suicide.
- Washington Post, AP