John Bolton will testify in Donald Trump's impeachment inquiry next week as Democrats will look for the former national security adviser to burn the president in his deposition.

Bolton is scheduled to testify on next Thursday, the DailyMail.com confirmed.

He was reported to be frustrated with efforts by Trump's personal attorney Rudy Giuliani to run a shadow foreign policy with the Ukraine and called the former mayor 'a hand grenade who's going to blow everyone up.'

Also testifying next week will be National Security Council legal adviser John Eisenberg and his deputy Michael Ellis. They are scheduled for Monday. The testimony was first reported by The New York Times.

It's unclear if Bolton's testimony is voluntary or if he will be issued a subpoena.

It's also unclear as to whether he will show up. The White House is likely to try to block his testimony - along with Eisenberg's and Ellis' - citing executive privilege.

Bolton could be a marque witness for Democrats and is in a strong position to testify as to whether there were any 'quid pro quos' for the Ukraine to receive nearly $400 million in American military aid.

Before Bolton comes before lawmakers, Tim Morrison, the top Russia official on Trump's National Security Council, is scheduled to testify on Thursday.

Morrison is expected to leave his White House post imminently, NPR reported on Wednesday.

Former National Security Adviser John Bolton is scheduled to testify in Donald Trump's impeachment inquiry next week

Bolton was reported to be frustrated with efforts by Trump's personal attorney Rudy Giuliani to run a shadow foreign policy with the Ukraine

The White House could cite executive privilege to try and keep Bolton from testifying against President Trump

Morrison's attorneys said he would appear before lawmakers if subpoenaed.

He was mentioned frequently by name when Bill Taylor, the top U.S. diplomat in the Ukraine, testified last week. Taylor testified that it was Morrison who told him that EU Ambassador Gordon Sondland told a top Ukrainian official that U.S. security aid to the Ukraine was dependent on officials there launching an investigation into a gas company that had Hunter Biden on its board.

Meanwhile, Bolton's attorneys have been speaking to the staff on the three committees handling the closed-door impeachment testimony to come up with an agreement for the former national security adviser to talk.

'Obviously he has very relevant information and we want him to testify,' House Intelligence Committee Chairman Adam Schiff said Sunday on ABC's 'This Week' of Bolton.

Bolton has the same attorney as Charles Kupperman, a former White House aide who defied a congressional subpoena this week and asked a federal court to rule on if he should follow the instructions of the legislative branch or the executive branch after the administration told him not to testify.

President Trump in September fired Bolton, who is known for his hardline stances on Washington's archenemies, particularly Iran, North Korea and Venezuela.

Bolton has been on the Democrats' wish-list for a witness after he was revealed to be critical of efforts within the administration and from Trump's allies to pressure the Ukraine into investigating Joe and Hunter Biden.

Bolton was so alarmed by the moves he alerted a lawyer, his former aide Fiona Hill testified last week in a congressional deposition behind closed doors.

Hill told lawmakers that Bolton said Giuliani, the president's point-man on Ukraine, was 'a hand grenade who's going to blow everyone up,' according to an account in The New York Times.

Following a 'sharp exchange' with Sondland, who was working with Giuliani on the pressure campaign, Bolton instructed Hill to notify a National Security Council lawyer.

Referring to acting White House chief of staff Mick Mulvaney, Bolton told Hill to relay a message to the chief lawyer for the National Security Council: 'I am not part of whatever drug deal Sondland and Mulvaney are cooking up.'

Additionally, Christopher Anderson, a State Department employee who was a special adviser on the Ukraine, testified on Wednesday that Bolton cautioned in a June 13 White House meeting that Giuliani 'was a key voice with the President on Ukraine which could be an obstacle to increased White House engagement.'

Christopher Anderson, a State Department employee, testified about Bolton warnings on Wednesday

Bolton's former deputy Fiona Hill testified last week that Bolton called Giuliani 'a hand grenade who's going to blow everyone up'

Anderson's opening statement, obtained by The Wall Street Journal, outlines staff efforts to shore up U.S.-Ukraine relations and support Volodymyr Zelensky's presidency in the wake of Ambassador Marie Yovanovitch's firing and a tweet from Giuliani sent shortly after Zelensky's election that claimed the new president was surrounded by enemies of President Trump.

Bolton's warning came before Trump's July 25 phone call with Zelensky that led to the impeachment inquiry, which is entering a new phase on Capitol Hill as lawmakers prepare to take the investigation public.

Anderson testified that in a June White House meeting, Bolton, who was national security adviser at the time, 'supported increased senior White House engagement' with the Ukraine in order to help them fight off Russian aggression.

Democrats are investigating an allegation Trump linked U.S. military aid to public declarations by Ukrainian President Volodymyr Zelensky that he would investigate Biden, his son Hunter Biden's tenure on the board of a Ukrainian energy company called Burisma, and a debunked conspiracy theory that Ukraine, and not Russia, meddled in the 2016 U.S. presidential election.

Trump has maintained he did nothing wrong, there was no quid pro quo, and the call was he had with Zelensky was 'perfect.'

Bolton would be a strong position to testify on those allegations given his former standing in the administration to date.

The Democrats are wrapping up the closed-door hearing phase of their impeachment hearings and preparing to make them public.

Bill Taylor, the top U.S. diplomat in the Ukraine whose closed-door testimony in the impeachment inquiry against Trump shocked Democrats with its details, is willing to testify in public when the hearings move to that stage.

No request has been made for his public testimony, CNN reports, but he is likely to be on the Democrats' list when the time comes.

Republican Leader Mitch McConnell blasted House Democrats' impeachment resolution on the Senate floor on Wednesday

Bill Taylor, the top U.S. diplomat in the Ukraine, is wiling to testify in public

BILL TAYLOR'S MOST DAMNING QUOTES ON TRUMP AND UKRAINE The following day, on September 8, Ambassador Sondland and I spoke on the phone. He said he had talked to President Trump as I had suggested a week earlier, but that president Trump was adamant that President Zelensky, himself, had to 'clear things up and do it in public.' President Trump said it was not a 'quid pro quo.' Ambassador Sondland said that he had talked to President Zelensky and Mr. Yermak and told them that, although this was not a quid pro quo, if President Zelensky did not 'clear things up' in public, we would be at a 'stalemate.' I understood a 'stalemate' to mean that Ukraine would not receive the much-needed military assistance. Ambassador Sondland said that this conversation concluded with President Zelensky agreeing to make a public statement in an interview with CNN. ON HOW TRUMP WANTED UKRAINE IN 'A BOX' ... in fact Ambassador Sondland said, "everything" was dependent on such an announcement, including security assistance. He said that President Trump wanted to put President Zelensky 'in a public box' by making a public statement about ordering such investigations. ON WHAT SONDLAND TOLD UKRAINE'S LEADERS FACE TO FACE Ambassador Sondland told Mr. Yermak that the security assistance money would not come until President Zelensky committed to pursue the Bursisma investigation. ON WHAT TRUMP WANTED ...on September 8, Ambassador Sondland and I spoke on the phone. He said he had talked to President Trump as I had suggested a week earlier, but that president Trump was adamant that President Zelensky, himself, had to clear things up and do it in public.' President Trump said it was not a 'quid pro quo.' ON TRUMP'S UNDERSTANDING OF QUID PRO QUO ...Ambassador Sondland tried to explain to me that President Trump is a businessman. When a businessman is about to sign a check to someone who owes him something, he said, the businessman asks that person to pay up before signing the check. Advertisement

Taylor testified last week that he was told that American military aid to the Ukraine was contingent on Kiev putting out a statement they were investigating the Bidens and the 2016 election.

Democrats believe he could be a star witness.

He's rock solid, detailed notetaker and unimpeachable,' Rep. Jackie Speier, a Democratic member of the House Intelligence Committee, told CNN. 'Fifty years given to his country -- it doesn't get much more 'Top Gun' than that.'

The House will vote on Thursday on an impeachment resolution that lays out the format for public hearings when that stage of the investigation begins.

The House Intelligence Committee will take the lead in the first round but there will be no role for the president's lawyers - a fact the White House and Republicans have blasted.

Under the resolution, power is concentrated in the hands of House Intelligence committee Chair Adam Schiff, who will ultimately produce a public report on the matter and decide what evidence to turn over to the House Judiciary Committee, which will be responsible for drawing up the formal articles of impeachment.

Senate Republican Leader Mitch McConnell blasted the procedure as denying the president his 'basic due process rights.'

'It does not confer on President Trump the most basic rights of due process,' McConnell complained in a speech on the Senate floor on Wednesday.

He also criticized the amount of power put in Schiff's hands when it comes to conducting the hearings.

'He's not even required to make all the evidence he obtains public,' McConnell noted. 'He alone gets to decide what evidence goes in his report. And the resolution doesn't even give the President any rights in the public hearing that it requires Chairman Schiff to hold.'

President Trump's attorneys will not get to participate in the process until it reaches the Judiciary panel stage - at that point Schiff's hearings will have played out on national television.

The White House on Tuesday launched a similar complaint about the lack of due process for the president.

'The White House is barred from participating at all, until after Chairman Schiff conducts two rounds of one-sided hearings to generate a biased report for the Judiciary Committee. Even then, the White House's rights remain undefined, unclear, and uncertain – because those rules still haven't been written,' White House press secretary Stephanie Grisham argued in a statement on the resolution.

Taylor, meanwhile, testified behind closed doors last week that Trump refused to release U.S. security aid or meet with Ukrainian President Volodymyr Zelensky until Zelensky agreed to investigate the president's political rivals.

Trump wanted a public commitment from the Ukraine they would investigate Burisma Holdings, a Ukrainian gas company with Hunter Biden on its board, Taylor - a Vietnam veteran and career State Department official - told Congress, and said the president wanted Ukraine 'put in a box.'

Trump and his allies have pushed an unproven theory Joe Biden, as vice president, demanded the Ukraine remove a prosecutor to the benefit of the company.

The president also pushed an unproven conspiracy theory that an email server belonging to the Democratic National Committee was hacked by Ukrainians during the 2016 election and they made it look as it were the Russians - a story, that if true, would indicate he won the 2016 contest without Russian interference.

House Intelligence Committee Chair Adam Schiff will be the face for the Democrats when the impeachment hearings go public

Bolton was in meetings with EU Ambassador Gordon Sondland on Ukraine policy

Taylor said he was told that Trump had made clear that military aid to help keep Ukraine safe from Russia would only be made available if Zelensky went public to order 'investigations,' otherwise there was a 'stalemate.'

And Taylor testified that Sondland told another diplomat: 'President Trump did insist that President Zelensky go to a microphone and say that he is opening investigations of Biden and 2016 election interference, and that President Zelensky should want to do this himself.'

The bombshell testimony rocked Washington D.C. and left the White House reeling - after Trump had started the day by calling impeachment 'a lynching.'

As Democratic lawmakers trickled out of the hearing, they called they evidence 'damning,' while Republicans had little to say.

Taylor called the involvement of Rudy Giuliani in a 'parallel' foreign policy 'highly irregular'; confirmed that John Bolton had called linking military aid to Ukraine to a Biden probe a 'drug deal'; implicated Mike Pence, Mike Pompeo and Mick Mulvaney in the scheme; and painted EU Ambassador Gordon Sondland as part of Giuliani's scheme as well as an error-prone official lax on security and an unreliable witness - who one Republican conceded is likely to be recalled to the probe.

He recalled a phone call with Sondland, whom the president put in charge of Ukrainian affairs despite that country not being an EU member.

'During that phone call, Amb. Sondland told me that President Trump had told him that he wants President Zelensky to state publicly that Ukraine will investigate Burisma and alleged Ukrainian interference in the 2016 election,' Taylor said in his statement.

He added Sondland told him 'everything' - meaning U.S. military aid and a White House meeting - was contingent on the Ukraine publicly agreeing to the probe.

'Amb. Sondland also told me that he now recognized that he had made a mistake by earlier telling the Ukrainian officials to whom he spoke that a White House meeting with President Zelensky was dependent on a public announcement of investigations — in fact, Amb. Sondland said, 'everything' was dependent on such an announcement, including security assistance,' Taylor said.

'He said that President Trump wanted President Zelensky 'in a public box' by making a public statement about ordering such investigations,'' he noted.

Taylor is considered the biggest threat to Trump to come before lawmakers.

He left his retirement to take up the top U.S. post in the Ukraine after Ambassador Marie Yovanovitch was fired by Trump. He has no ties to the administration and no diplomatic career to worry about given his senior statesman status.

He has worked in administrations for both political parties.