The Democratic chairman of the House judiciary committee, Jerry Nadler, has not ruled out including evidence from the Mueller report in articles of impeachment against Donald Trump that could be published as early as next week.

On Sunday, Nadler told CNN’s State of the Union evidence showed the president’s conduct in the Ukraine scandal was part of “a pattern”, indicating “that the president put himself above this country several times”.

On Monday Nadler’s committee will hold a critical hearing. Democratic and Republican lawyers from the House intelligence committee will testify following a months-long investigation of the president’s attempts to have Ukraine investigate a political rival for his own political gain.

Nadler said on Sunday Democrats had presented “a very rock solid case” that Trump abused his power, and would get “a guilty verdict in three minutes flat” if the case was presented to a jury.

He has suggested that after the hearing concludes his committee will work quickly to publish impeachment articles, which could be voted on before Christmas.

The scope of these articles has been the centre of significant debate in the Democratic party, with a number of centrists elected in swing districts keen to keep the focus on Ukraine rather than broader evidence included in the Mueller report into Russian election meddling in 2016, which documented evidence of attempted obstruction of justice by the president.

While Nadler made no commitment to including evidence from Mueller, he argued on CNN that Trump “sought foreign interference in our election several times both in 2016 and in 2020. That he sought to cover it up all the time. And that he continually violated his oath of office.

“And that all this presents a pattern that poses a real and present danger to the integrity of the next election.”

Other senior Democrats, including the House intelligence committee chairman, Adam Schiff, appeared to urge their colleagues to keep the impeachment articles focused on Ukraine.

Appearing on CBS’ Face the Nation, Schiff, a former US government prosecutor, said it had been his “guiding philosophy” to “charge those that is the strongest and most overwhelming evidence and not try to charge everything even though you could charge other things”.

For impeachment to pass the Democrat-controlled House and move to a trial in the Republican-controlled Senate, two votes are required. First, the House judiciary committee must vote with a simple majority to confirm a resolution that the full House should vote on the articles of impeachment. Then the full House most vote on the articles of impeachment, with a simple majority required to impeach the president.

Nadler’s committee released a report on Saturday laying out the constitutional grounds for impeachment, an update to reports published in 1974 and 1998 during impeachment proceedings against Richard Nixon and Bill Clinton.

Shortly after the report’s publication, Trump once again branded the inquiry “a witch-hunt” and “a total hoax”.

Over the weekend, Trump told reporters that his personal attorney, Rudy Giuliani, would provide Congress and the attorney general, William Barr, with “a report” containing “a lot of good information” about his recent trip to Ukraine.

Giuliani, who holds no official title in the White House, is at the centre of the Ukraine scandal for his role in an unofficial diplomatic back channel tasked with pushing the Ukranian president, Volodymyr Zelenskiy, into investigating the former vice-president Joe Biden as well as an unfounded conspiracy theory suggesting Ukraine was involved in election meddling during 2016.

Giuliani’s trip to Ukraine, reported this week, drew criticism after he met with a number of former officials central to the impeachment inquiry.

On Sunday, Republicans loyal to Trump defended the president from all allegations of impeachable behaviour and, in the case of the Texas senator Ted Cruz on NBC’s Meet the Press, continued to push the line that Ukraine interfered in the 2016 election.

But they also criticised Giuliani’s travel to Ukraine. The Florida congressman Matt Gaetz described the decision as “weird” and suggested that Trump had confirmed Giuliani would appear before Congress, despite the White House blocking most involved in the scandal from testifying.

Cruz captured the tenor of Republican defences of Trump – and pointed to his likely survival in office – when he told NBC: “This is a kangaroo court. In the House, they’re going to impeach, not because they have the evidence but because they hate the president [and] want to [undo] the election.

“But it’s going to go to the Senate, it’s going to go nowhere, and I think the American people know this is a waste of time and this is Democrats putting on a circus.”

From the White House, Trump tweeted a complaint about procedure in the House, writing: “When you can’t win the game, change the rules!”