As opinion polls show Americans bitterly divided over whether to impeach Trump, the Judiciary Committee in the Democratic-controlled House of Representatives will hold a hearing on Wednesday to explain to the public what constitutes an impeachable offense.
Such articles would be drafted by Nadler's committee and then voted on by the full House.
The House Judiciary Committee is planning to hold its first hearing on impeachment Wednesday.
Trump and Republicans continue to brand the accusations and process as a political "witch hunt".
But Cipollone also did not rule out White House participation in the hearings entirely, instead requesting further details from Nadler on how the inquiry will be conducted and saying he will give him an answer by next Friday.
"We can not fairly be expected to participate in a hearing while the witnesses are yet to be named and while it remains unclear whether the Judiciary Committee will afford the President a fair process through additional hearings".
Secretary of State Mike Pompeo said Monday it's "very unfortunate" the judiciary committee is holding its hearing at the same time that Trump is representing the U.S.at the North Atlantic Treaty Organisation summit.
Cipollone's letter applied only to the Wednesday hearing, and he demanded more information from Democrats on how they meant to conduct further hearings before Trump would decide whether to participate in them.
Democrats have said they don't want to get tied up in lengthy court battles to force those witnesses to cooperate with subpoenas.
"The first and foremost person who needs to testify is Adam Schiff", Collins said while adding that Schiff had "compared himself to a special counsel".
Three contenders are emerging for impeachment articles against Trump, according to major media reports.
"What I thought was really interesting is, in his letter, Adam Schiff does not mention any specific crime-no mention of bribery, no mention of extortion, no mention of quid pro quo", he said. It should bring together legal experts whose testimony, along with the report of the Intelligence Committee, could lay the groundwork for possible indictment articles, which the panel is expected to develop shortly. Lawmakers are also examining whether the Republican tied a White House meeting or aid for Ukraine to those investigations.
The inquiry was set off by reports that an anonymous intelligence staffer filed a complaint that Trump allegedly misused his power by withholding aid to Ukraine in favor of politically advantageous investigations, which Trump and officials in Kyiv have denied.
A Senate trial will be the last and final stage. The report will describe the evidence gathered by the Intelligence, Foreign Affairs and Supervision committees. "The report-along with any Minority Views - will then be forwarded to the Judiciary Committee pursuant to H.Res. 660". "That's not my thing", Zelensky said.
Trump has previously suggested that he might be willing to offer written testimony under certain conditions, though aides suggested they did not anticipate Democrats would ever agree to them.
Members of the commission were given the opportunity to read it before a vote on Tuesday to send it to the Judicial Commission for Wednesday's historic hearing.
"So I think you can read text", he said.
But the White House counsel asked if the Democratic-led committee will allow Republicans to choose the witnesses and will the president's counsel be allowed to cross-examine fact-witnesses, even those who had testified earlier.
Still, Republican Rep. Tom McClintock of California, a Judiciary Committee member, said he believes Trump would benefit if he presents his own defense. "That is his right", McClintock said on ABC's This Week.
But Micklethwait said the publication will still investigate the Trump administration, calling it "the government of the day".