The newly released transcripts of October testimony from William Taylor, the top U.S. diplomat to Ukraine, give a window into the next phase of the impeachment inquiry. Taylor will be the first witness to return to Capitol Hill and testify in an open hearing Nov. 13.

What Taylor has already said behind closed doors and what questions lawmakers are asking offer clues about what evidence Democrats and Republicans will bring forward to the public hearings.

Here are five topics from Taylor’s testimony that will likely be revisited in next week’s open session:

1) “Highly irregular” diplomacy channels 

Democrats will likely ask Taylor to rehash descriptions he gave in October of the two channels of diplomacy that emerged in Ukraine — a traditional channel through the State Department and National Security Council and a second channel led by Trump’s personal lawyer, Rudy Giuliani.

Taylor was alarmed by the latter, which he called “weird.” He walked investigators through conversations he had with U.S. diplomats in both channels.

Taylor raised concerns that the second channel was “conditioning an important component of our assistance on what would ultimately be a political action,” and creating a schism between the priorities of U.S. diplomats and those of Giuliani, who was trying to get a commitment from Ukrainian leaders to investigate Trump’s political rivals.

TAYLOR: The irregular channel seemed to focus on specific issues, specific cases, rather than the regular channel’s focus on institution building. So the irregular channel, I think under the influence of Mr. Giuliani, wanted to focus on one or two specific cases, irrespective of whether it helped solve the corruption problem, fight the corruption problem.

[INTELLIGENCE CHAIRMAN ADAM B. SCHIFF]: And those two cases you mentioned, the Burisma and the Bidens and the 2016 election, those were both individual investigations that were sought by Mr. Giuliani because he believed it would help his client, the President of the United States, right?

TAYLOR: That’s my understanding.

Taylor described Giuliani as having a corrosive effect on U.S. officials who dealt with him as part of the irregular channel, including Kurt Volker, the former special envoy to Ukraine.

In response to questions from Republican staff, Taylor said that he’s known Volker for about 20 years and confirmed that he views him as “a man of integrity.”

When asked if Volker always acted “in the best interests of the United States,” he wavered.

“When he got involved with Mr. Giuliani, I think that that pulled him away from or it diverted him from being focused on what I thought needed to be focused on, that is yeah,” Taylor said “So, in general, yes, but the Giuliani factor I think affected Ambassador Volker.”

2) Broad opposition to assistance hold 

A large portion of Taylor’s testimony focuses on the congressionally approved U.S. security assistance for Ukraine that was withheld for months. Democrats have honed in on this as evidence of a quid pro quo — that Trump would only deliver the aid if Ukraine opened an investigation into his rivals.

Taylor was uncomfortable with using that phrasing in his testimony but said it was his “clear understanding” that the aid would not flow until Ukraine President Volodymyr Zelenskiy committed to an investigation. A White House meeting Trump promised Zelenskiy in a May 29 letter congratulating him on his election win also seemed conditioned on such an investigation, he said.

“Being careful about my use and understanding of quid pro quo, which is imperfect at best, the facts were that these relationships between the announcement and the meeting or phone call and the meeting and then the security assistance, it was clear to me that there was that relationship,” he said.

Taylor first learned about the security assistance issue during a July 18 video conference call led by the National Security Council. A female Office of Management and Budget staffer, whom Taylor could not identify, said the agency had received a directive from acting White House Chief of Staff Mick Mulvaney, passed on by the president, to hold the aid.

“In an instant, I realized that one of the key pillars of our strong support for Ukraine was threatened,” he said.

After that call, the hold was discussed in a series of NSC-led interagency meetings. “At every meeting, the unanimous conclusion was that the security assistance should be reassumed (sic), the hold lifted,” Taylor said.

Taylor detailed the strong opposition throughout the administration — seemingly with the exception of Trump and Mulvaney — to the aid being withheld.

He described an unprecedented State and Defense departments’ effort to release the aid without OMB’s clearance. The Defense Department was asked to evaluate the effectiveness of the aid, Taylor said, describing one interagency meeting in which Laura Cooper, deputy assistant secretary of Defense, presented a strong case about how the assistance was helpful to U.S. interests.

Former National Security Adviser John Bolton was working with secretaries of both departments, as well as the CIA director, to get the decision reversed, Taylor said.

Taylor was never given a reason for the hold and throughout July and August he did not make a connection to the investigations. He testified that he was “embarrassed” that he could not provide the Ukrainians with an explanation.

It was not until early September, when Vice President Mike Pence met with Zelenskiy in Warsaw, Poland, that Taylor learned from Tim Morrison, the NSC’s top adviser on Russia and Europe, about communications that seemed to connect the security assistance to the investigations.

Pence alluded vaguely to it when he told Zelenskiy Trump wanted the Ukrainians to do more to fight corruption, Taylor said Morrison told him. A separate meeting in Warsaw between Gordan Sondland, U.S. ambassador to the European Union, and Andriy Yermak, a Zelenskiy adviser, was more explicit. Sondland said security assistance would not come until Ukraine committed to pursue a probe of Burisma, the energy firm tied to Hunter Biden, the son of former Vice President Joe Biden, according to what Morrison told Taylor.

Sondland told Taylor in a phone call the following day that “Trump wanted President Zelensky in a box by making [a] public statement about ordering such investigations,” although Sondland later said Trump explicitly said he was not asking for a quid pro quo.

Throughout these events Taylor was contemplating resigning over concern about tying foreign aid to domestic politics, which he called “crazy.” Ultimately, the aid was released on Sept. 11 without Zelenskiy having committed to an investigation.

3) Zelenskiy under pressure?

Democrats will be interested in hearing more about a July 20 phone call Taylor had with Ukrainian Defense Secretary Oleksandr Danyliuk.

“He conveyed to me that President Zelensky did not want to be used as a pawn in a U.S. reelection campaign,” Taylor told lawmakers.

Taylor’s description of the call undermines the idea repeated by Trump that Zelenskiy felt no pressure or concern about the requests for investigations.

But Taylor also remained concerned Zelenskiy would give into Trump’s demands. In a Sept. 13 meeting, two days after the hold on U.S. security assistance was lifted, Taylor warned the Ukrainian president that launching the investigations would be a bad idea.

“I had just said to President Zelensky, bipartisan support of Ukraine in Washington is your most valuable strategic asset, don’t jeopardize it. And don’t intervene — don’t interfere in our elections, and we won’t interfere in your elections,” he told congressional investigators. “I had just said that to President Zelensky, and on the way out I said the same thing to Andriy Yermak. And the body language was such that it looked to me like he was still thinking they were going to make that statement.” (Yermak is a top aide to Zelenskiy.)

Taylor was referring to Sondland telling him that Zelenskiy committed to announcing the investigation in a CNN interview. Although the security assistance had been released, a White House meeting Trump had promised Zelenskiy had still not been scheduled.

4) Do all roads really lead to Russia 

Speaker Nancy Pelosi has frequently communicated her concerns that with Trump “all roads” lead back to Russia and his fondness for President Vladimir Putin. So it would not be surprising if Democrats use Taylor to explain why the decisions Trump made surrounding Ukraine could be seen as helpful to Russia.

A batch of text messages between top State Department officials previously released by the committees showed one in which Taylor describing a  scenario in which Ukraine gives an interview committing to investigations Trump wanted and didn’t receive the security assistance that was being withheld — a scenario Taylor said Russia would love and would drive him to quit.

Taylor elaborated on that text in his testimony, saying his “nightmare” was that Zelenskiy would commit to investigating Biden and other conspiracy theories, “take all the heat from that, get himself in big trouble in this country and probably in his country as well, and the security assistance would not be released.”

With the Russians “leaning” on Ukraine, Taylor said the Kremlin is interested in any assistance the Ukrainians receive, but especially support from the Americans.

“So the Russians are loving, would love, the humiliation of Zelensky at the hands of the Americans,” he said, explaining that “would give the Russians a freer hand” and drive him to quit his post.

Taylor had previously described his hesitation to return as envoy to Ukraine — a position he held in the early 2000s — after Ambassador Marie Yovanovitch was recalled, saying he only agreed to do so under the circumstances that the U.S. continued to provide strong support to Ukraine in its defense against Russia. He said the scenario he described would be equivalent to throwing Ukraine under the bus and that he wanted no part of that.

5) Republicans pursue a different focus

Republicans, committed to defending the president and denying any quid pro quo, will be seeking to undermine the evidence Democrats try to display in open hearings.

The transcripts released this week show that a key argument Republican lawmakers and staff made behind closed doors is that Ukrainian officials did not know that U.S. aid was being held up at the time of the July 25 phone call between Trump and Zelenskiy.

“If nobody in the Ukrainian Government is aware of a military hold at the time of the Trump-Zelensky call, then, as a matter of law and as a matter of fact, there can be no quid pro quo, based on military aid,” Rep. John Ratcliffe, R-Texas, told Taylor.

An exchange like this one between Ratcliffe and Taylor will likely be a feature of Republican strategy for the open hearings:

TAYLOR: July 25th is a week after the hold was put on the security assistance. And July 25th, they had a conversation between the two Presidents, where it was not discussed.

RATCLIFFE: And to your knowledge, nobody in the Ukrainian Government was aware of the hold?

TAYLOR: That is correct.

RATCLIFFE: Great. Thank you for clarifying.

Republican staff later asked Taylor if there were any concerning activities coming from the irregular diplomatic channel after the funds started to flow.

“Not that I can remember,” Taylor said.

Devin Nunes, the top Republican on the Intelligence Committee, has asked multiple witnesses about Ukrainian connections to the Hillary Clinton campaign for president in 2016 and the “Steele dossier,” including Taylor.

Republicans pursued a line of questioning focused on certain Ukrainian officials who have spoken negatively about Trump, as well as questions about whistleblowers, and those issues are likely to reemerge in the public sessions.