(AP) -- Frustrated with his troubled candidacy, Donald Trump is hinging his presidential hopes on a risky bet: that the fiery populism and freewheeling style that won him the Republican nomination give him a better shot at the White House than uniting his party and rallying moderate voters.

Trump underscored that conviction Wednesday with a staff overhaul at his campaign's highest levels, the second shake-up in the past two months. The Republican nominee tapped Stephen Bannon -- a combative conservative media executive with no presidential campaign experience -- to serve as CEO of his White House bid.

Pollster Kellyanne Conway, who has known Trump for years and gained his trust during her brief tenure working for the businessman, will serve as campaign manager.

The moves are aimed in part at marginalizing campaign chairman Paul Manafort, a longtime Republican operative who pushed Trump to moderate his tone and improve relations with skeptical Republican officials. In breaking with that approach, Trump appears set on finishing the race on his own terms-- win or lose.

Manafort's past work for a pro-Russian Ukrainian political party has also become a potential liability for Trump. The Associated Press reported Wednesday that Manafort helped the party secretly route at least $2.2 million in payments to a pair of prominent Washington lobbying firms.

While Manafort maintains his title, Trump allies made clear Bannon will be overseeing the campaign staff and operations.

"He believes he should stay true to what got him this far," said David Bossie, the leader of a pro-Trump super PAC. "It's essentially, 'dance with the one who brung ya.'"

Rarely do presidential campaigns undergo this level of tumult at this stage of the general election. Wednesday's announcements come less than three months before Trump's Election Day faceoff with Democrat Hillary Clinton, and roughly six weeks before early voting begins.

Conway downplayed the notion of internal dissent at campaign headquarters at Trump Tower, telling the AP the staffing changes are "an expansion at a critical time in the homestretch."

In the aftermath of the shake-up, Trump spent the day in New York surrounded by senior staff, including his new hires. He convened a security roundtable, attended by allies including former New York Mayor Rudy Giuliani, and received his first classified national security briefing at a FBI field office in lower Manhattan.

Trump's standing in the White House race has plummeted throughout the summer and he now trails Clinton in preference polls of most key battleground states. He's struggled to offer voters a consistent message, overshadowing formal policy speeches with a steady stream of controversies, including a public feud with an American Muslim family whose son was killed while serving in the military in Iraq.

Clinton, campaigning Wednesday in Cleveland, said voters should not be fooled by any Trump efforts to revamp his candidacy.

"There is no new Donald Trump," Clinton said. "This is it."

According to Republicans close to Trump, the campaign shake-up is aimed more at allowing him to fully embrace the aggressive style that helped him with the primary rather than taking a more restrained, traditional approach.

While Trump's first staff shuffle in June was driven by concerns among top Republicans, as well as the candidate's children, this latest upheaval appears to come directly from the businessman. Republicans say he's grown angry with his sinking poll numbers and frustrated that many GOP lawmakers remain skeptical of his candidacy.

Several Republicans discussed the personnel changes on the condition of anonymity, because they were not authorized to publicly disclose internal thinking.

Trump vented his frustration during a weekend fundraiser in the Hamptons. He was encouraged to bring Bannon on board by Rebekah Mercer, a member of a prominent GOP fundraising family that has close ties to the Breitbart executive. Conway also has ties to the Mercers.

Bannon has circled Trump's orbit in recent years and has been in touch with aides to the billionaire throughout the campaign. Bannon's website has been fiercely loyal to Trump for months and sharply critical of Republican leaders, including House Speaker Paul Ryan. Breitbart has also actively promoted false conspiracy theories about Clinton, some that have then made their way into Trump's remarks.

Bannon has grown particularly close to Corey Lewandowski, who was ousted as campaign manager in the June shake-up that gave Manafort control of the operation.

Lewandowski stays in contact with Trump, but is so despised by the candidate's three oldest children -- all of whom are influential advisers -- and is seen as such a divisive figure that it would be all but impossible for him to formally return.

Conway, a longtime Republican strategist and pollster, joined Trump's campaign earlier this year as a senior adviser and quickly earned Trump's trust. She's also close with daughter Ivanka Trump and her husband, Jared Kushner, another influential voice in the candidate's inner circle.

Kevin Kellems, a longtime Republican strategist, called Conway "the complete package." Kellems, who briefly worked for Trump's campaign, said the decision to promote the pollster and hire Bannon suggests Trump "wants to win and is willing to make the changes necessary to do so."

Manafort has spent months trying to ingratiate Trump to Republican lawmakers who have urged the billionaire businessman to dial back his fiery rhetoric and run a more traditional campaign. While Trump held a handful of meetings with Washington Republicans and fulfilled requests from GOP leaders to raise campaign cash, he's continued to rankle lawmakers with his numerous controversies.

Rick Gates, who has been traveling often with Trump, is expected to maintain a senior role with the campaign. Other staff is also expected to be brought on in the coming days.

Conway said that Trump has a history of beating expectations and can't be counted out.

"August is not October, let alone November," she said.

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Pace reported from Washington. Associated Press writer Julie Bykowicz contributed to this report.

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