Washington (CNN) Rep. Adam Schiff and the rest of the House impeachment managers were meeting in the speaker's office in the US Capitol late Sunday afternoon when the bombshell news broke. The New York Times reported that a book manuscript John Bolton submitted to the White House for review alleged that President Donald Trump told his then-national security adviser that he wanted to continue holding military aid to Ukraine until the country helped with investigations into Democrats -- including former Vice President Joe Biden.

Rep. Adam Schiff, Rep. Hakeem Jeffries, Rep. Jerry Nadler and other House Managers meet in their ante room off the floor of the Senate before walking to the Sente floor for the start of the day's session of the Senate impeachment trial on January 23.

"It was one of those moments where everyone freezes," Schiff told CNN Monday morning. "We all reacted to the story. There were several exclamations that I wouldn't want to repeat in print."

The Bolton news is the latest bit of information to shape the ongoing Senate trial in real time. The ever-shifting dynamics mean the House Democrats prosecuting the case against the President have needed to be nimble, focused and prepared. Their task is clear: to present a case to convict Trump of abuse of power and obstructing Congress over his dealings with Ukraine. But the job of convincing Republicans remains fluid, particularly as the President's own legal team continues its opening arguments amid the Bolton revelation.

Their work begins each weekday around 11 a.m., when the managers and their team convene in the speakers' office. According to two people with knowledge of the meetings, the seven managers and their staff have turned the ornate, spacious office of Speaker Nancy Pelosi into their de facto headquarters. They gather there to hold rolling prep sessions and make final alterations to speeches, rehearse lines, review slides and go over the hundreds of video cues that have been peppered into their hours-long presentation.

Shortly before the 1 p.m. session begins each day, the managers cross over to the Senate side of the Capitol in a silent, informal procession that is a rough approximation of their seniority on the team. The lead manager, Schiff, walks at the head of the line, with Judiciary Chairman Rep. Jerry Nadler typically a half step behind. Following them, and flanked by staff, are the remaining managers: Reps. Zoe Lofgren, Hakeem Jeffries, Val Demings, Sylvia Garcia and Jason Crow.

The House impeachment managers meeting in House Speaker Nancy Pelosi's office suite at the Capitol in Washington, January 20.

Over 24 hours spread out over three full days last week, often for up to nine hours a day, the team laid out their arguments in meticulous fashion, weaving hundreds of hours of testimony and reams of evidence into a well-structured story about their views of what the President did, why he did it, and why he deserves to be removed from office.

Their weeks of work, including much of the holiday recess spent holed up in the Capitol, was undertaken even as the outcome of the trial -- acquittal of Trump by the Republican Senate majority -- seemed all but inevitable. While there were certainly moments that seemed to capture even some of the President's staunchest allies in the Senate chamber, there were also times the Democrats stepped out too far and offended the same GOP senators they are trying to win over.

One subject they're anticipating is Republican senators' desire to bring up Hunter Biden , both as a line of questioning and as a potential witness.

"We know already this is going to be an issue," one source familiar with the ongoing preparations told CNN. There is no evidence of wrongdoing by either Joe or Hunter Biden.

Given the Bolton news, Democrats are now renewing their push for witnesses.

"There can be no doubt now that Mr. Bolton directly contradicts the heart of the President's defense and therefore must be called as a witness at the impeachment trial of President Trump," the managers said in a statement released Sunday night.

In reality, the Democratic managers are appealing to two audiences: the 100 senators sitting before them in the chamber but also the American public watching or listening at home. If a critical mass of GOP senators can't be convinced of the President's wrongdoing, the Democrats can hope to reach voters nine months before the next election.

Observations from the press gallery as well as interviews with eight sources on Capitol Hill reveal how the House Democrats prepared for a marathon stretch of arguments in the first week of the impeachment trial, and how their performances were perceived.

Like a federal criminal prosecution

Democratic Reps. Zoe Lofgren of California and Jerry Nadler of New York are seen in the ante room.

The Democratic team is a mixture of backgrounds and personalities. Among the managers are freshman lawmakers and seasoned veterans of the House. Four are men and three are women. All are lawyers except Demings, a retired police officer from Florida. Some hail from deep-blue districts while others occupy swing seats in red states.

While their diversity is apparent, it's been clear who has driven the strategy . The two chief architects of the Democratic approach are Schiff and his top counsel on the Intelligence Committee, Daniel Goldman. Both are former federal prosecutors -- Schiff in the Central District of California and Goldman in the prestigious Southern District of New York. Those who know Goldman say that pedigree is reflected in how House Democrats have conducted their case.

"They are doing this right out of the federal prosecutor's playbook," said Elie Honig, a CNN contributor and a former prosecutor in the SDNY who worked with Goldman as well as another attorney on the team, Daniel Noble. Honig pointed to the way the managers have presented videos and documents from the impeachment hearings to contextualize their arguments.

Daniel Goldman is the top lawyer for the House Intelligence Committee

"It's a hallmark of certainly the SDNY way," Honig said.

Danya Perry, another former prosecutor at the SDNY who worked with Goldman, told CNN that the Democrats' arguments during the trial "seemed to have his fingerprints all over them."

"Like some of Danny's jury addresses, Chairman Schiff's remarks packed some passion and some soaring language, but for the most part they were straightforward, plainspoken, and to the point," Perry said.

Staff work behind the scenes

Supreme Court Chief Justice John Roberts presides over the Senate impeachment trial on Tuesday, January 21.

Inside the Senate chamber during the trial, the managers sit cramped into small chairs at three adjoining tables. Most of them face the Democratic senators and with their backs to the presiding chair, Chief Justice John Roberts. Four to five staffers sit across from the managers, poring over thick folders of materials. The tables are frequently covered in papers.

When one manager speaks from the podium in the middle of the chamber, the others generally remain seated, listening or reading. Seated next to Schiff is a staffer with a laptop, whose primary role appears to be clicking through each slide or video clip for the presentation.

Invisible even to observers in the gallery is the anteroom off the Senate chamber, where the bulk of the Democratic staff works to supplement the team on the floor. Full of snacks, computers and printers, the anteroom is also the source of the rotating staffers who switch out into the chamber periodically.

The amount of preparation is reflected in how smoothly the presentations went. The managers rarely have to interrupt to direct a staffer moving through the slides.

It has helped that the staff work has been doled out in an orderly way.

Preparing the trial materials -- creating hundreds of slides, organizing more than 200 video clips, and writing more than 24 hours of oral arguments -- has been split along committee lines, one person familiar with the situation told CNN. Staffers from the House Intelligence and Judiciary committees focused on the article accusing the President of abusing his power, while staff from the House Oversight Committee worked largely on the article concerning the obstruction of Congress.

Communications for the team, including frequent background calls with reporters, has fallen to the staff members of both the Intelligence Committee and the speaker's office. Judiciary, meanwhile, has taken the lead on the legal briefs that were filed for the trial.

The most effective prep work has been the culling of hours of impeachment hearing testimony and other relevant video, such as clips of Trump's own words. The video clips break up the managers' speeches and have noticeably reignited interest from listless senators.

One surprise deployment of this tactic came Friday afternoon, as the managers were arguing about the importance of the strategic alliance with Ukraine. Lawmakers turned to look at the two screens on either side of the chamber's back wall, where the familiar face of former Sen. John McCain beamed out . As Schiff tossed to the sound of McCain, senators looked genuinely surprised (and some comforted) by the late Republican senator's presence in the chamber.

Still, despite the deft use of audio-visuals, the Democratic team has at times struggled to keep their audience engaged . The week was marked by senators coming and going from the chamber, despite rules suggested they should stay throughout. Those who remained often seemed distracted, playing with fidget-spinner toys, reading books, talking amongst themselves and passing notes.

At least two GOP senators, Jim Risch of Idaho and Richard Shelby of Alabama, appeared to nod off at their desks at some point during the week.

Mixed reactions

Rep. Adam Schiff and other House Managers walk to the Senate floor from their ante room (off the floor of the Senate) for the start of the day's session of the Senate impeachment trial on January 23.

When the House Democrats did manage to grab the attention of the chamber, it did not always help their case. Most often, this happened when they departed from the sober, just-the-facts tone and let their emotions get the best of them.

The most notable instance came after midnight on Wednesday morning toward the end of a marathon session, when Nadler chastised Republican senators opposed to allowing witnesses in the trial as "voting for a cover-up." The comment sparked a heated back-and-forth between Nadler and White House counsel Pat Cipollone, which in turn prompted a rebuke from the usually staid Chief Justice Roberts.

Nadler's remark also angered two key Senate Republicans, Susan Collins of Maine and Lisa Murkowski of Alaska, both of whom the Democrats need on their side to have any chance of hearing from witnesses next week.

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"I took it as very offensive. As one who is listening attentively and working hard to get to a fair process, I was offended," Murkowski said Wednesday, according to an aide.

Some Republicans have expressed appreciation for a few of the managers. One Republican aide told CNN the best advocate for the Democrats' case among the managers has been Jeffries, the New York Democrat and an experienced litigator. Sen. Lindsey Graham, who himself served as a manager during the impeachment trial of Bill Clinton in 1999, even congratulated Schiff Wednesday night for doing a "good job."

Indeed, Schiff had perhaps his best moment while wrapping up his remarks Thursday night. At one point, appearing to get choked up , he invoked the framers of the Constitution and offered his generous thanks to senators who had not been as attentive as they might have been.

"Having watched you now for three days, whether it is someone you are predisposed to agree with or predisposed not to, it is abundantly clear that you are listening with an open mind," Schiff said. "And we can't ask for anything more than that, so we are grateful."

Whatever goodwill Schiff may have earned with Republican senators appears to have dried up the following evening. Several left the chamber angry that the lead manager had cited a CBS News report that Republicans had been warned " your head will be on a pike " if they voted against the President.

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"That's where he lost me," Murkowski told reporters Friday. "He was moving right along with the good oratory, and then he got to a couple places and it was just unnecessary."

Did a stray remark after more than 26 hours of speeches damage all the work of the House Democratic team? Or was all of the preparation for naught, given how little chance there has ever been for Republicans to cross their President and vote to undermine his case?

Asked by CNN's Jake Tapper on "State of the Union" if using the line was a "mistake," fellow manager Lofgren said she doesn't know if it was.

"But hopefully the senators are not going to be letting a -- quoting a CBS report which Adam himself said (he) didn't know if that was accurate in making a decision for the country in whether the President has committed high crimes and misdemeanors," Lofgren said. "I can't believe the President's misbehavior would be ignored because of something like that."