Donald Trump’s presidential campaign endured another day of internal disruption Friday when Paul Manafort, who as campaign chairman had sought to build bridges with the Republican establishment by encouraging a more temperate and consistent message by the Republican nominee, abruptly resigned after a staff shake-up that had reduced his role.

The decision came during a critical week in the campaign, with Trump under pressure from Republican leaders and wealthy contributors to rebalance his candidacy after two weeks of missteps that have left him trailing Hillary Clinton in both national and battleground state polls.

Manafort’s departure leaves the campaign more firmly under the guidance of newly installed chief executive Stephen Bannon, formerly of Breitbart News, and veteran pollster Kellyanne Conway, who was elevated to campaign manager earlier in the week. The resignation came as Manafort faced increased scrutiny over his earlier work in Ukraine in behalf of pro-Russian forces, including the former president, Viktor Yanukovych.

Whether Manafort’s resignation will lead to additional staff changes was not clear on Friday morning. The longtime GOP strategist had recruited a number of former associates to join the campaign after he arrived last spring and it was not immediately known whether others would leave or be encouraged to do so as a result of his surprise decision.

The resignation was formally announced as Trump was preparing to tour the devastation from extraordinary flooding in Louisiana. The candidate said in a statement, “This morning Paul Manafort offered, and I accepted, his resignation from the campaign. I am very appreciative for his great work in helping to get us where we are today, and in particular his work guiding us through the delegate and convention process. Paul is a true professional and I wish him the greatest success.”

The news followed a Thursday night rally in North Carolina in which the candidate expressed regret for some of the harsh language he has used during the campaign. Trump’s language represented a sharp change in tone by a candidate who has resisted any such moves in the past. Trump’s words were applauded by mainstream Republicans, who hope this marked a transition to a campaign focused on attacking Clinton and delivering a consistent message about national security, law and order and the economy.

Friends of Manafort said Friday they believed he was undone by the combination of revelations about his work in behalf of those pro-Russian forces and the elevation of Conway and Bannon to Trump’s new inner circle.

“If you had had one of these things happen, it would have been survivable. But you had two of these things in concert,” the strategist said. “One thing I don’t think Trump will tolerate is the focus being on someone else rather than himself.”

Manafort’s background finally caught up with him. Associates of Manafort said Friday that it was clear that he was taking a calculated risk by joining Trump’s campaign. Said one, “He knows he’s been doing this stuff. It was going to become an issue. He wasn’t prepared to tamp it down. When he decided to re-enter high profile American politics, and he ratcheted it up with lots of Sunday shows and TV appearances. He had to know he was putting himself out there as a target.”

Members of Trump’s family, which has been an important part his inner circle, praised Manafort after the announcement, but made clear that controversies around him played a role in his decision to leave.

“I think my father didn’t want to be, you know, distracted with whatever things” Manafort was dealing with, said Eric Trump, Trump’s son, to Fox News. “My father just didn’t want to have the distraction looming over the campaign and quite frankly looming over all the issues that Hillary is facing right now.”

Jared Kushner, husband of Donald Trump’s daughter Ivanka Trump, has also become less enthusiastic about Manafort’s management, according to Trump’s aides. Kushner gave his blessing Tuesday to the campaign changes and has told Trump privately that Manafort had difficulties with aspects of executing the Republican National Convention and with building Trump’s organization nationally, the aides said.

Coupled with Trump’s own frustrations, the family’s souring on Manafort’s leadership created an atmosphere that was less supportive, though not hostile, of the operative, the aides said.

When Trump met with family and friends Sunday at Trump National Golf Club in Bedminster, N.J., he fumed about news reports and leaks following a Saturday fundraiser in The Hamptons where donors voiced concern about Manafort and the campaign. When he reached out to Bannon and Conway about elevated roles, his family did not intervene, the aides said.

Trump’s campaign team has been in a near-constant state of upheaval since last spring, when Manafort joined the operation. He clashed immediately with then-campaign manager Corey Lewandowski and eventually prevailed in a power struggle that saw Lewandowski depart the Trump team after playing a central role in helping the novice politician win the Republican primaries.

Manafort was initially tasked with developing a strategy to assure Trump nailed down the number of delegates needed for a first-ballot victory at the Republican convention in Cleveland and also was in charge of helping to plan the convention program.

On May 19, after Trump collected the necessary number of delegates to lock up the nomination, Trump promoted Manafort to the position of campaign chairman, a clear slight to Lewandowski. One month after that, Trump fired Lewandowski on June 20, clearing Manafort to run the campaign.

Manafort had repeatedly signaled to members of the Republican establishment that he and Trump were working together to rebrand the candidate in a more presidential light. But hopes of a so-called “pivot” vanished as the summer wore on and Trump appeared intent on settling scores with former rivals within his own party and critics.

Perhaps most damaging was Trump’s attack on a Gold Star family – who lost their son, Army Capt. Humayun Khan, while he served in Iraq – for speaking out against him at the Democratic National Convention. He later refused to apologize or express regret, although he did say late Thursday that he was sorry if he had caused “personal pain” for unspecified comments.

But aside from Trump’s own missteps, Republican strategists also became increasingly concerned that the campaign, under the direction of Manafort, had failed to build out a robust infrastructure in key battleground states. Though the campaign is relying heavily on the Republican National Committee for its ground game, lackluster efforts by the main campaign have left Trump underprepared for the competitive general election.

Lewandowski, now a paid consultant to CNN, focused on that problem in an appearance on the cable network soon after Manafort’s resignation was public. “It’s been widely reported that 1/8there3/8 has not been a robust ground effort in states like Florida, that that had not been laid out yet,” he said. “You cannot blame the candidate for those things. Those things fall squarely on the staff at some level of building up the field teams and hiring the people.”

Manafort also played a key role in trying to reposition Trump for the general election, trying to strike a balance between the volatile and unpredictable Trump of the primaries and a more even-keeled candidate many GOP officials and donors hoped to see as he moved toward the general election. But those efforts created friction with the candidate, who on several occasions publicly indicated that he would not change.

Still, to some Republicans outside the Trump operation, Manafort’s departure will leave a void in the campaign. “Any semblance of the sort of structured political advice he was going to get from Manafort is going to be gone now,” said one strategist who knows Manafort. “You don’t have a voice in those meetings any longer that has presidential experience.”

Manafort is leaving on good terms with the campaign, and will remain an ally and outside confidant of the campaign, according to a close associate of his who spoke on the condition of anonymity Friday to The Washington Post. Manafort has had an easy rapport with both Conway and Bannon in meetings this week but was inclined to leave to give them room to develop and execute their own strategy, the aides said.

Manafort’s move took some by surprise because they thought that even though he had been lowered on the staff hierarchy, he would stay on as an adviser. “He didn’t seem like he was going to do it,” said one person familiar with Manafort’s thinking as of Wednesday night. “He said, ‘Look I think I can still help Donald.'”

Manafort’s personal business dealings have also come under intense scrutiny in recent weeks, amid damaging questions over his ties to foreign governments and indications that he might have received $12.7 million in undisclosed cash payments. The alleged payments, which Manafort denied, were noted in a ledger kept by Yanukovych’s political party. Since then, more evidence has surfaced that raised concerns about his ties to pro-Russian politicians in Ukraine.