Chief Justice of the United States John Roberts blocked Kentucky Republican Sen. Rand Paul from posing a question during the Senate impeachment trial Wednesday that would have named the alleged whistleblower at the center of the case, Fox News is told — and Paul may try to force the issue during the question-and-answer session that begins Thursday afternoon.

Roberts, for now, has ball control because he actually receives the questions in note cards from senators, then reads the question aloud in the Senate chamber to be answered by either House Democratic managers or Trump's defense team. But Fox News has learned Roberts may soon lose his grip on the proceedings amid a torrent of criticism both inside and outside the Senate.

The Federalist co-founder Sean Davis condemned what he called Roberts' "arbitrary and unilateral censorship of senators and Senate business," and reported that Roberts had initially sought to block even general questions of the intelligence community whistleblower. When Republicans threatened a vote rebuking and overriding Roberts, Davis reported, Roberts backed down and decided only to prohibit mentioning the whistleblower's name.

A reporter for Roll Call observed that during a break in the trial Wednesday, Paul was fuming.

"I don't want to have to stand up to try and fight for recognition," Paul shouted, according to reporter Niels Lesniewski, who noted that Paul's complaint was "audible from the galleries above the chamber."

"If I have to fight for recognition, I will," Paul said.

Asked by Fox News whether Paul, who has long raised concerns about possible intelligence community overreach, would press the issue during the upcoming question period, a spokesman for the senator told Fox News only, "tbd" -- short for "to be determined." Last year, Paul was vocal about wanting testimony from the whistleblower on the record, as inconsistencies emerged in the whistleblower's claims.

"If I have to fight for recognition, I will." — Kentucky GOP Rep. Rand Paul

Roberts, under the Constitution, presides over the impeachment trial. But the precise contours of his authority are not clearly established, and remain up for debate; Democrats have even said they will attempt a long-shot motion to give Roberts the unprecedented power to approve or reject witnesses, for example.

'GAME OVER': TRUMP DECLARES VICTORY AFTER BOLTON VIDEO EMERGES SHOWING HIM PRAISING UKRAINE CALL

Federal law protects whistleblowers only from retaliation in the workplace, and does not ensure their anonymity; and Republicans have disputed whether this particular whistleblower would even qualify for those limited protections, saying his complaint concerns a policy dispute and does not allege criminal or civil wrongdoing by the president.

Republicans have sought more information on the whistleblower ever since the intelligence community's internal watchdog found several indicators that the person might have a political bias. Fox News has previously reported the whistleblower is a registered Democrat and had a prior work history with a senior Democrat running for president. Additionally, the whistleblower faces an ICIG complaint for allegedly violating federal law by raising money ostensibly to pay for his legal fees, including money that could be coming from from foreign sources.

The whistleblower's attorney, Mark Zaid, openly admitted back in 2017 that a "coup" had started against the president from within the administration, and that CNN's coverage would play a "key role" in the effort.

He also openly solicited intelligence community members to help impeach and "get rid" of Trump, years before Trump's call with Urkaine's leader that triggered the current impeachment proceedings.

Additionally, Zaid acknowledged that the whistleblower had contact with a prominent Democratic presidential contender, amid reporters that he had served closely with Joe Biden when he was vice president. Trump's alleged pressure on Ukraine to investigate Biden is at the center of the current probe.

Conspicuously, Democrats' lead House impeachment manager Rep. Adam Schiff, D-Calif., has made public inconsistent statements concerning the House Intelligence Committee's contacts with the whistleblower. Schiff first denied that his panel had such contact, then reversed course and admitted that members of the committee had spoken to the whistleblower.

SCHIFF, IN REVERSAL, ADMITS HE SHOULD HAVE BEEN CLEAR ABOUT HIS OWN CONTACT WITH THE WHISTLEBLOWER

It could be, Republicans have asserted, that the whistleblower coordinated his complaint with Schiff's panel for partisan reasons -- a disclosure that, if true, would likely undermine the credibility of the impeachment proceedings and possibly expose Schiff to his own "abuse of power" allegations. Thus far, the impeachment effort has arguably been elevated in importance from normal partisan bickering in part by the gravitas afforded to the supposedly well-meaning whistleblower at the center of the case.

On Wednesday, Schiff again denied knowing the identity of the whistleblower, while Republicans accused him of deliberately lying. Schiff repeatedly shut down GOP questions during the House impeachment proceedings concerning White House leaks -- even though doing so at one point seemingly demonstrated that Schiff likely knew the whistleblower's identity.

“Lietenant Colonel Vindman, did you discuss the July 25 phone call [between Trump and Ukraine's president] with anyone outside the White House on July 25 or the 26 and if so, with whom?” Republican California Rep. Devin Nunes asked last year.

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“Yes. I did,” Vindman, who has also claimed not to know the whistleblower's identity, responded. He said he had spoken to Deputy Assistant Secretary George Kent but, before he could mention the other person, Schiff intervened and urgently blocked the questioning.

“We need to protect the whistleblower," Schiff interjected. "Please stop. I want to make sure that there is no effort to out the whistleblower through these proceedings. If the witness has a good faith belief that this may reveal the identity of the whistleblower, that is not the purpose that we’re here for. I want to advise the witness accordingly.”

'COUP HAS STARTED,' UKRAINE WHISTLEBLOWER'S ATTORNEY PROMISED IN 2017, VOWING TO IMPEACH AND 'GET RID OF' TRUMP

Roberts has mostly stayed out of the spotlight in the trial. In the first day of the proceedings, Roberts admonished both sides for misconduct in the chamber, saying their rhetoric had gotten too heated. That warning reportedly came after a "stunned" Maine Republican Sen. Susan Collins passed a note to Roberts, following Democrats' claims that a vote against their witness resolution would amount to a "coverup."

Dershowitz takes on Nadler, Schiff

Wednesday's lengthy question-and-answer session contained other notable moments, including another spirited constitutional argument by liberal Harvard Law Professor Alan Dershowitz.

Multiple media outlets, including CNN, mischaracterized Dershowitz throughout the day as saying that presidents can do "anything" as long as they can argue it's in the "public interest." Additionally, several politicians, including Sen. Cory Booker, D-N.J., falsely claimed that Dershowitz argued Trump's conduct was "OK."

In fact, Dershowitz maintained that criminal or criminal-like conduct is impeachable, regardless of its motivation. And he did not endorse Trump's behavior. Instead, Dershowitz asserted the Senate should not be in the business of removing elected presidents based on nebulous and unconstitutional "abuse of power" or "obstruction of Congress" charges that the framers expressly rejected.

It would be a standard Democrats would not want applied to their own presidents, he argued. (Neither "abuse of power" nor "obstruction of Congress" is a defined crime.)

To demonstrate that point, Dershowitz made thinly veiled references to President Obama's refusal to send lethal military aid to Ukraine, as well as his failed, unenforced "red line" warning for Syria not to use chemical weapons. Obama was also caught on a hot microphone promising Russia's president he would have "more flexibility" on missile defense issues after the 2012 election.

"Let's consider a hypothetical," Dershowitz said. "Let's assume that President Obama had been told by his advisors that it really is important to send lethal weapons to the Ukraine. But then he gets a call from his pollster and his political adviser, who says we know it's in the national interest to send lethal weapons to the Ukraine, but we're telling you that the left-wing of your party is really going to give you a hard time if you start selling lethal weapons and potentially get into a lethal war with Russia. Would anybody here suggest that is impeachable?"

WATCH: DERSHOWITZ TURNS TO HOUSE DEMS, UNLOADS CONSTITUTIONAL ARGUMENT IN DRAMATIC MOMENT AT IMPEACHMENT TRIAL

He continued: "Or let's assume President Obama said, 'I promise to bomb Syria if they had chemical weapons. But I'm now told by my pollster that bombing Syria would hurt my electoral chances.' Simply not impeachable at all."

It would be difficult if not impossible, Dershowitz said, to determine that a president has acted with corrupt "motive," given that countless presidents inevitably consider both the national interest and their personal political gain when making decisions. Rarely do presidents act with purely corrupt or purely noble motives, he said. Often, he went on, presidents want to help themselves but in doing so believe they are also helping the country.

There were signs Dershowitz's argument was making headway among moderate swing-vote GOP senators. Collins, R-Maine, was reportedly "clearly unhappy" with Democrats' explanation as to why they had not charged actual crimes in the articles of impeachment, and was shaking her head while they answered her question on the topic by claiming their allegations were "akin" to criminal conduct, Roll Call's Todd Ruger reported.

When House Democratic impeachment manager Jerry Nadler, D-N.Y., claimed "all scholars" except for Dershowitz agreed that impeachment didn't have to involve crimes or criminal-like conduct, there were audible groans from the GOP side of the chamber.

Dershowitz rose, turned to Nadler, and said he was simply ignorant of the facts.

"By the way, the congressman was just completely wrong when he said I'm the only scholar who supports this position," Dershowitz said. "In the 19th century, which is much closer in time [to the founding of the country and the drafting of the Constitution,] Dean [Theodore] Dwight of the Columbia Law School wrote that 'the weight of authority,' by which he meant the weight of scholarly and judicial authority, this is in 1867, is in favor of requiring a crime. Justice [Benjamin Robbins] Curtis came to the same conclusion."

Dershowitz reiterated that the "abuse of power" charge was vague and indeterminate, and was precisely the kind of article of impeachment that the framers wanted to reject -- as evidenced by their explicit repudiation of the charge of "maladministration,' which he said is synonymous with "abuse" or "misconduct" in office.

He then took a shot at fellow Harvard Law School professor Laurence Tribe for being a partisan hack, and warned that scholars often have partisan biases, too. Dershowitz noted that he voted for Hillary Clinton and would be making the same argument if she were on trial.

Later, Dershowitz deployed another hypothetical to argue that Democrats' impeachment was itself, somewhat ironically, a partisan proceeding. That Biden was running for president, Dershowitz said, in fact gave Trump a plausible public policy justification for seeking a probe into possible corruption by the former vice president while in office.

"Let’s assume hypothetically that the president was in his second term and he said to himself, you know, Joe Biden is running for president," Dershowitz said. "I really should now be concerned about whether his son is corrupt, because he’s not only a candidate ... but he could be the President of the United States, and if he’s the president of the United States and he has a corrupt son, the fact that he’s announced his candidacy is a very good reason for upping the interest in his son."

WHOOPS: BIDEN CAMP TOUTS UKRAINE ACTIVIST WHO CALLED HUNTER BIDEN'S ACTION'S THERE 'VERY BAD'

Dershowitz continued: "If he wasn’t running for president, he’s a has-been. He is the former vice president of the United States. Okay, big deal. But if he’s running for president, that’s an enormous big deal. So the difference the House managers would make is whether the president’s in his first term or his second term, whether he’s running for reelection or not running for reelection. I think they would have to concede that if he was not running for reelection, this would not be a corrupt motive, or it would be a mixed motive, but leaning on the side of national interest. If he is running for reelection, suddenly that turns it into an impeachable offense!”

Schiff rose to claim that Republicans surely would have impeached Obama if he sought to tie financial aid to a foreign country to secure a probe into Mitt Romney; he did not address Dershowitz's argument that such an impeachment, too, would be improper, especially if there was some evidence of potential overseas misconduct by Romney.

Trump declares 'GAME OVER'

A string of newly resurfaced video clips of former national security adviser John Bolton spurred Trump and his supporters Wednesday to highlight what they described as Bolton's serious credibility questions amid the Senate impeachment trial, as the president tweeted, "GAME OVER!"

In his tweet, Trump linked to an interview of Bolton in August 2019 where he discusses Ukraine policy. In the Radio Free Europe/Radio Liberty interview clip, Bolton made no mention of any illicit quid pro quo, and acknowledged, as Republicans have claimed, that combating "corruption" in Ukraine was a "high priority" for the Trump administration.

Bolton also called Trump's communications with Ukrainian President Volodymyr Zelensky "warm and cordial," without mentioning any misconduct. It seemingly contradicted reported assertions in Bolton's forthcoming book that Trump explicitly told him he wanted to tie military aid to Ukraine to an investigation into Joe and Hunter Biden. (Zelensky has said his communications with Trump involved no pressure for any investigation.)

Fox News later identified clips of Schiff, D-Calif., now the lead House impeachment manager, in which he says Bolton had a distinct "lack of credibility" and was prone to "conspiracy theories." This week, Schiff said Bolton needed to testify in the impeachment trial as an important and believable witness.

WHITE HOUSE TELLS BOLTON TO REMOVE HIGHLY CLASSIFIED MATERIALS FROM MANUSCRIPT, THROWING TESTIMONY INTO DOUBT

"This is someone who's likely to exaggerate the dangerous impulses of the president toward belligerence, his proclivity to act without thinking, and his love of conspiracy theories," Schiff told MSNBC's Rachel Maddow on March 22, 2018, when Trump named Bolton national security adviser.

"And I'll, you know, just add one data point to what you were talking about earlier, John Bolton once suggested on Fox News that the Russian hack of the DNC [Democratic National Committee] was a false flag operation that had been conducted by the Obama administration," he said. "So, you add that kind of thinking to [former U.S. attorney] Joe diGenova and you have another big dose of unreality in the White House."

Schiff made similar arguments back in May 2005, saying in an interview with CNN's "Crossfire" that Bolton was "more focused on the next job than doing well at the last job" when he was up for nomination as ambassador to the United Nations under then-President George W. Bush.

"And particularly given the history, where we've had the politicizing of intelligence over WMD [weapons of mass destruction], why we would pick someone who the very same issue has been raised repeatedly, and that is John Bolton's politicization of the intelligence he got on Cuba and other issues, why we would want someone with that lack of credibility, I can't understand," Schiff had said.

Bolton himself had admitted in the past that he would be more than willing to lie if he felt it was in the nation's best interest.

“If I had to say something I knew was false to protect American national security, I would do it," Bolton said in an interview with Fox Business in 2010.

But, speaking to CNN on Monday, Schiff took a different approach -- calling Bolton essential to the "search for truth."

"I think for the senators, and I'm just not talking about the four that have been so much the focus of attention, for every senator, Democrat and Republican, I don't know how you can explain that you wanted a search for the truth in this trial and say you don't want to hear from a witness who had a direct conversation about the central allegation in the articles of impeachment," Schiff said on CNN's "New Day."

WHITE HOUSE TELLS BOLTON TO REMOVE HIGHLY CLASSIFIED MATERIALS FROM MANUSCRIPT, THROWING TESTIMONY INTO DOUBT

Seemingly responding to charges of hypocrisy, Schiff remarked on the Senate floor late Wednesday: "I'm no fan of John Bolton, but I like him a little more now than I used to."

Witnesses up in the air

Whether or not the Senate will vote to call Bolton as a witness -- or whether he will legally be able to testify -- remain open questions. Enthusiasm on Captiol Hill for Bolton's testimony dampened somewhat following Trump's release of the "GAME OVER!" clip.

Republicans have suggested that Schiff himself, and Hunter Biden, should testify, if Democrats insist on Bolton.

And, Republicans have argued that Democrats should not need additional witnesses, if they truly believe that their case is "overwhelming" and already proven "beyond any doubt," as Nadler and other Democratic impeachment managers have said.

Any witness resolution would likely require four Republican defections in the Senate, because in the event of a 50-50 tie, Chief Justice of the United States John Roberts is highly likely to abstain rather than assert his debatable power to cast a tie-breaking vote.

The witness question will be decided later this week, after the question-and-answer session of the trial wraps up.

Republicans, who have a 53-47 majority in the chamber, have suggested to Fox News that they would amend any witness resolution that subpoenas Bolton to also require the appearance of several additional witnesses favorable to the Trump administration -- likely killing support in the Senate for the whole witness package altogether.

Republicans have also pointed out that in the House, Democrats approved mostly Democratic witnesses, and afforded few to their GOP colleagues. In the Senate, some commentators have argued, it would be fair play to tilt the ratio in the other direction.

In the meantime, concerns over Bolton potentially divulging classified information, as well as violating the legal principle of executive privilege, have emerged. On Wednesday, the White House revealed it had told Bolton not to publish his upcoming tell-all book about his time in the Trump administration until classified material is removed from the manuscript.

“Under federal law and the nondisclosure agreements your client signed as a condition for gaining access to classified information, the manuscript may not be published or otherwise disclosed without the deletion of this classified information,” Ellen J. Knight, a National Security Council (NSC) aide, wrote in a letter to Bolton attorney Charles J. Cooper last week, which was obtained by Fox News.

Bolton’s book has disrupted Trump’s impeachment trial. The New York Times reported that Bolton's draft manuscript includes a claim that Trump explicitly linked a hold on military aid to Ukraine to an investigation of Joe and Hunter Biden -- a central part of the case against Trump.

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The letter from the NSC was transmitted to Bolton’s attorney on Jan 23. The New York Times article about the manuscript came out on Sunday, Jan. 26 -- three days after the letter was transmitted. That indicates that the NSC had already made the determination that there was top secret information in Bolton’s manuscript before anything became public.

Earlier in the day, CNN reported that the letter amounted to a threat against Bolton. But sources told Fox News this was not a “threat,” saying the letter merely points out that there is top secret information contained in the manuscript that cannot be released to the public.

Fox News' Chad Pergram and Sally Persons contributed to this report.