Democrats in the U.S. House of Representatives were expected to unveil two articles of impeachment against Republican President Donald Trump on Tuesday, a senior Democratic aide said, setting the stage for a possible vote this week on impeachment.

Articles of impeachment are expected to be drafted on abuse of power and on obstruction of Congress, the aide told Reuters. The Washington Post first reported the expected articles, citing three unidentified officials.

House Speaker Nancy Pelosi's office has confirmed that House Committee officials will hold a press conference on Tuesday morning to announce the next steps in the impeachment inquiry.

'Clearly impeachable'

Democrats had on Monday sought to bolster the case for impeaching Trump, describing his pressure on Ukraine to investigate a political rival as a "clear and present danger" to national security and the upcoming U.S. election. 

The roughly nine-hour hearing in the U.S. House of Representatives Judiciary Committee was punctuated by shouting and recriminations from Trump's fellow Republicans. 

The committee's Democratic chairman Jerry Nadler said there was extensive proof of Trump's wrongdoing.

"The facts are clear. The danger to our democracy is clear, and our duty is clear," Nadler said in his closing statement at the last scheduled House impeachment hearing.

Trump "constitutes a continuing threat to the integrity of our elections and to our democratic system of government," Nadler added. "Such conduct is clearly impeachable. This committee will proceed accordingly."

If the House approves the articles, as expected, the Republican-controlled Senate will hold a trial to decide whether to remove the president from office. A conviction is considered unlikely.

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In drafting the articles of impeachment, Pelosi is facing a legal and political challenge of balancing the views of her majority while hitting the Constitution's bar of "treason, bribery or other high crimes and misdemeanors." 

Pelosi met with her leadership team behind closed doors Monday evening. A crucial decision was whether to include an obstruction charge from special counsel Robert Mueller's findings as some liberals want or keep the impeachment articles focused on Ukraine as centrist Democrats prefer.

Republicans said there was no proof Trump improperly pressured Ukraine to investigate former U.S. Vice President Joe Biden, a leading Democrat in the 2020 presidential race.

"They're desperate to have an impeachment vote on this president," said Representative Doug Collins, the top Republican on the panel.

They also argued there was no firsthand evidence Trump withheld 391 million U.S. dollars in military aid or a White House meeting to get his Ukrainian counterpart to investigate Biden and his son, Hunter Biden, as well as a debunked theory that Ukraine, not Russia, interfered in the 2016 U.S. election. 

Trump denies wrongdoing and has called the impeachment probe a hoax.

Republicans repeatedly called for testimony by Intelligence Committee Chairman Adam Schiff, whose panel led the investigation and held five days of hearings last month. Nadler rejected Republicans' request to call Schiff as a witness, so Republicans put up a poster with his picture on a milk carton under the word, "Missing."

The White House has refused to participate in the hearings in the House because it says the process is unfair. Nadler denied Republicans' request for eight witnesses to appear before the inquiry, saying they were either not necessary for Monday's hearing or beyond the scope of the inquiry.

Democrats argued vigorously that Trump's meaning could not have been clearer in seeking political dirt on Biden, his possible opponent in the 2020 election.

(With input from agencies)