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House Democrats have laid out the constitutional grounds for their case to impeach President Donald Trump, as the process gathers pace.

A report by the judiciary committee setting out the legal and historical basis for impeachment comes ahead of Monday's public hearing to consider evidence against Mr Trump.

A vote on articles of impeachment could be held as early as next week.

On Saturday, Mr Trump again described the process as a "witch-hunt".

The impeachment process began in September after an anonymous whistleblower complained to Congress about a July phone call by Mr Trump to the president of Ukraine, in which the president appeared to tie US military assistance to Ukraine launching investigations which would help him politically.

Democrats say that that this amounted to inviting a foreign power to intervene in the US election to help the president win another term.

What does the new report say?

The House Judiciary Committee's 52-page report, written by its Democratic staff, lays out what Democrats see as the constitutional argument for impeaching the president.

Unlike a recent report from the intelligence committee, it does not present evidence and testimony against him - but rather builds the case that will be made about how the founding fathers conceived impeachment and when it is justified.

It also aims to rebut some of the key defences made by Republicans and the White House against how the process has been conducted.

"The Framers [America's founding fathers] worst nightmare is what we are facing in this very moment," tweeted Jerry Nadler, the Democratic chairman of the judiciary committee.

"President Trump abused his power, betrayed our national security, and corrupted our elections, all for personal gain. The Constitution details only one remedy for this misconduct: impeachment."

The report comes after the committee was told this week by three constitutional law experts that there is no doubt that President Trump's actions required him to be removed from office.

But one expert, the only one picked by Republicans, disagreed that Mr Trump's actions were impeachable, though he said they were wrong.

Impeachment - all you need to know

What is Mr Trump accused of?

Democrats say Mr Trump dangled two bargaining chips to Ukraine to obtain investigations he wanted - $400m (£300m) of military aid that had already been allocated by Congress, and a White House meeting for President Volodymyr Zelensky.

The first investigation Mr Trump wanted from Ukraine was into former Vice-President Joe Biden, his main Democratic challenger, and his son Hunter. Hunter Biden joined the board of a Ukrainian energy company when his father was President Obama's deputy.

The second Trump demand was that Ukraine should try to corroborate a conspiracy theory that Ukraine, not Russia, had interfered in the last US presidential election. This theory has been widely debunked, and US intelligence agencies are unanimous in saying Moscow was behind the hacking of Democratic Party emails in 2016.

Democrats say the pressure on a vulnerable US ally constitutes an abuse of power.

Republicans in turn accuse them of carrying out a politicised inquiry and say witnesses who testified are biased against Mr Trump.

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Where are we in the process?

The impeachment process moved this week from the House Intelligence Committee to the House Judiciary Committee, after the former released its report to lawmakers that was designed to lay out the evidence to remove Mr Trump from office.

The judiciary committee is now in the process of drawing up formal articles of impeachment against Mr Trump and could vote on them by Friday.

That would set up a vote before the full Democrat-held House of Representatives on whether to impeach the president. If that happens, the Senate will be forced to hold a trial - possibly early in January.

A Senate vote requires a two-thirds majority to convict and remove the president - unlikely in this case, given that Mr Trump's party controls the chamber.

Only two US presidents in history - Bill Clinton and Andrew Johnson - have been impeached, but neither was convicted and removed from office.

President Richard Nixon resigned before he could be impeached.

Learn more about the impeachment inquiry