Washington (CNN) The White House is entering a pivotal phase of impeachment proceedings amid internal consternation over legal strategy and fresh apprehension at how President Donald Trump will react to hours of televised testimony.

The ostensible top aide in the White House, acting chief of staff Mick Mulvaney, sowed bafflement and griping this week at his legal maneuvering over whether to comply with congressional demands he be interviewed as part of the impeachment efforts.

Coverage of the scramble aggravated Trump, according to people familiar with the matter, who was frustrated at the perception he was pitted against his own chief of staff. Mulvaney ultimately reversed course Tuesday morning and fell in line with the White House to avoid further disruption, according to a person familiar with his thinking.

For many in the White House, it was an unnecessary subplot that only highlighted lingering internal divisions -- both with the top lawyers inside the West Wing and with ousted national security adviser John Bolton. Bolton's team rebuffed Mulvaney's attempts to join a lawsuit meant to determine whether the acting chief of staff could testify and that would have given Mulvaney legal cover for at least a month.

The Bolton team's opposition to Mulvaney ultimately left him out in the cold legally on a weekend after witnesses had pointed to him as a key player in the alleged arrangement to coerce Ukraine into investigating Trump's political rivals.

Mulvaney's recent moves are "incomprehensible," a person close to the White House said, and have created more questions than answers.

The White House and Mulvaney's lawyers declined to comment.

The moves have led to differing accounts from each side. A person familiar with Mulvaney's thinking insisted he was acting in close coordination with the White House counsel's office as he took the legal steps. But a source close to the White House denied the two camps were aligned, and said the counsel's office raised objections before the suit was filed, though could not instruct Mulvaney how to proceed.

The dust-up came as aides are bracing for several days of public hearings -- and the ensuing news coverage -- they believe could distract Trump and cause him to lash out. Even in an administration used to high-profile hearings and distracting chaos, the weight of the upcoming several weeks is not lost.

"This is the biggest political fight in a generation," one White House ally said.

Another 'hoax'

Already, Trump has derided the impeachment efforts as a hoax meant to undermine him. On Tuesday he lambasted Democrats as focusing on the probe rather than taking up his North American trade deal.

"Democrats in Washington would rather pursue outrageous hoaxes and delusional witch hunts -- which are going absolutely nowhere, don't worry about it -- than pass the USMCA and deliver real stuff for the American workers," he told the Economic Club of New York in a lunchtime speech.

Back in Washington, aides were busy wrapping their heads around the Mulvaney developments, which earlier this week caused Trump to complain when he saw news coverage suggesting Mulvaney was defying him (people close to Mulvaney were quick to deny he was doing anything of the sort, with one White House official saying the filing "in no way indicates any distance between the President and the acting chief").

The legal maneuvers also angered the White House counsel's Office. Mulvaney and White House counsel Pat Cipollone have engaged in a long-simmering feud over impeachment strategy, each blaming the other as ineffective in preventing Trump's current predicament.

Last week, Mulvaney defied a congressional subpoena to appear in closed testimony. Investigators want to hear from him after multiple witnesses named him as a key orchestrator of the alleged Ukraine quid pro quo.

Mulvaney has encouraged other administration officials to defy congressional subpoenas. But instead of simply defying his own, he asked a judge to decide whether he should adhere to White House guidance he not cooperate -- and risk being held in contempt of Congress — or comply with the demand.

He attempted to join a lawsuit brought by a deputy of Bolton's to settle the question. But this week, Bolton's lawyer made clear Mulvaney wasn't welcome to join, and sought to have him removed. The lawsuit will still be considered by a judge through at least mid-December, without Mulvaney's involvement.

Mulvaney initially said he would bring his own lawsuit. But on Tuesday he said he wouldn't, announcing in a court filing he would follow the White House instructions not to cooperate with the investigation.

The White House counsel's office was perplexed and outraged with the strategy, the person close to the White House said, asking "what the hell is he doing?" as Mulvaney went about the legal positioning.

This source said Mulvaney's moves are further exacerbating existing tensions between the counsel's office and the acting chief of staff, who have been deeply at odds over how to handle the growing impeachment crisis. Though the counsel's office was given forewarning about the initial move to join the lawsuit, there wasn't any agreement it was a good idea, the source said.

"Optics-wise, it just adds to the chaos stories coming out," another person close to the White House said. One source called Mulvaney's recent actions a "plot twist."

Internal wrangling

People familiar with Mulvaney's strategy denied his moves went against what the White House expected. When Mulvaney was figuring out his response to the House subpoena Friday, he huddled with his newly hired private lawyers and lawyers from the White House counsel's office to consider various approaches, according to a source familiar with Mulvaney's thinking.

While Mulvaney's allies insist the counsel's office didn't disagree with his plan to join the suit, other White House officials say there were objections raised. In one of these instances, the White House didn't want Mulvaney suing the President, his boss, and so Mulvaney planned to name the House as defendants if he had filed a lawsuit.

"Never did they object" to Mulvaney filing in court, according to the person familiar with Mulvaney. "He very much values their input and their thoughts. They knew everything."

Even last night, when Mulvaney was planning to sue the House, the White House counsel's office didn't object to it. But a source close to the President's legal team says concerns about the overall strategy were raised beforehand and that the White House counsel's office is limited in what it can tell the acting chief of staff to do.

Still, fallout from Mulvaney's legal maneuvering has led some White House staffers to questions about why Cipollone didn't push harder to convince Mulvaney not to file suit in the first place.

The quibbling Tuesday has led to questions about Cipollone's confidence in his legal argument that aides can defy Democratic requests. White House officials insist they remain assured in their standing to instruct administration not to cooperate.

The differing accounts and open resentments lay bare a divided West Wing as the impeachment enters its public phase. Ever since Trump released a transcript of his phone call with Ukraine's president in September, advisers have privately grumbled about a lack of strategic thinking as witness after witness defied the White House's edict not to cooperate.

Some people close to the White House have claimed Trump lacks advisers who can successfully steer him away from troublesome decisions, like releasing the transcript of his phone call with Ukraine's president.

"He's pushed out all the people who gave him pushback," one source said.

Mulvaney in particular has come under scrutiny, particularly following his October news conference when he admitted there was a quid pro quo with Ukraine and shrugged it off as the normal course of business.

That, too, infuriated the President. But as the impeachment crisis envelops the White House, there is a belief among aides that Mulvaney will remain in his role at least for now as Trump seeks to avoid further chaos. Mulvaney has taken less of a role in managing the White House impeachment strategy as senior adviser and son-in-law Jared Kushner and Cipollone lead those efforts.

Two new advisers -- former Treasury official Tony Sayegh and former Florida attorney general Pam Bondi -- have been in the process of joining the President's team for days, and are expected to be in place before the public hearings begin.

Anticipation

On Wednesday, as two career diplomats appear in the first televised impeachment hearings on Capitol Hill, Trump will be hosting Turkish President Recep Tayyip Erdoğan at the White House. The meetings will occupy much of the midday, but aides acknowledge the President will likely catch the beginning of the hearings in the morning and later watch news coverage from the White House residence.

White House lawyers have poured through transcripts from the closed-door depositions as they build their case, trying to determine what to expect from the public phase.

Trump's allies view the hearings as a test of Democrats' -- and particularly House Intelligence Chairman Adam Schiff's -- ability to piece together a case against Trump. Already, Republicans have laid out a strategy undercutting several key arguments made by Democrats, insisting in a memo on Tuesday that Trump was right to try combating corruption in Ukraine.

Most of the President's allies acknowledge he's likely to be impeached by the Democrat-led House. That's led some to begin preliminary discussions about what the White House will do once the case goes to the Senate, including pushing for a motion to dismiss. Some have also raised the prospect of adding more lawyers to the legal team once the Senate trial begins.

The White House is expected to do what it has for past high profile public hearings: live monitoring of the public hearing, frequent real time updates to staff and frequent dissemination of talking points to surrogates.

Trump's campaign will also use the hearings to highlight moments between witnesses and Republican lawmakers, hoping to boost moments when witnesses get jammed up in their answers or drawing out contradictions between what they've said in the past and what they say during the hearing.

One source likened the effort to the campaign's work surrounding the Democratic primary debates -- albeit with drastically higher stakes.