US President Donald Trump has dismissed the impeachment inquiry as a "big fat hoax".
He was responding to today's announcement by the US Speaker of the House Nancy Pelosi that articles of impeachment against him are to be drafted.
Mr Trump is being accused of pressuring Ukraine to investigate a political rival.
In a televised statement earlier, Ms Pelosi said that the president's abuse of power "leaves us no choice but to act".
The move is a historic step that sets up a fight over whether to oust Mr Trump from office.
At the end of the news conference, Ms Pelosi took strong exception to a reporter's question as to whether she hated the US President.
The reporter explained he was asking because some Republicans have said a dislike of Mr Trump is driving impeachment.
"I don't hate anybody," she answered.
"I was raised in a Catholic house. We don't hate anybody. Not anybody in the world. So don't you accuse me," she said, pointing at the reporter.
Ms Pelosi criticised the US President on policy, calling him a "coward" on failing to take steps against gun violence, "cruel" for seeking to remove protections for "Dreamers" immigrants and "in denial" about climate change.
But Ms Pelosi said those were issues to be settled in an election, while the impeachment inquiry was aimed at preventing abuses of presidential power as outlined in the US Constitution.
"This is about the Constitution of the United States and the facts that led to the president's violation of his oath of office," she said, tapping the podium for emphasis.
She also said that she continued to pray for the president.
"As a Catholic, I resent your using the word hate in a sentence that addresses me. I don't hate anyone. I was raised in a way that is ... a heart full of love, and always pray for the president," Ms Pelosi added.
"So don't mess with me when it comes to words like that."
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Mr Trump responded to Ms Pelosi's comments with a Twitter post, saying, "Nancy Pelosi just had a nervous fit," adding that she hated his accomplishments under his administration.
"She hates that we will soon have 182 great new judges and sooo much more. Stock Market and employment records," he added.
"She says she 'prays for the President'. I don't believe her, not even close. Help the homeless in your district Nancy," Mr Trump wrote, adding "USMCA?" - a reference to a pending trade agreement with the United States and Canada that Ms Pelosi has not brought to the House floor for a vote.
Nancy Pelosi just had a nervous fit. She hates that we will soon have 182 great new judges and sooo much more. Stock Market and employment records. She says she "prays for the President." I don't believe her, not even close. Help the homeless in your district Nancy. USMCA?
— Donald J. Trump (@realDonaldTrump) December 5, 2019
By asking the House Judiciary Committee chairman to draw up the charges, Ms Pelosi, the top congressional Democrat, signalled that a formal impeachment process against the 45th president is all but assured.
With a majority of members in the Democratic-controlled chamber already signalling their intent to back the deeply divisive procedure, Mr Trump is likely to become just the third president in US history to be impeached by the House of Representatives.
"Sadly, but with confidence and humility, with allegiance to our founders and a heart full of love for America, today I am asking our chairman to proceed with articles of impeachment," Ms Pelosi said in a short, sombre televised statement.
'Today I am asking our chairman to proceed with articles of impeachment' - US House of Representatives Speaker Nancy Pelosi said she has instructed the House Judiciary Committee to proceed with the impeachment inquiry against President Donald Trump pic.twitter.com/9NC95hwBA0
— RTÉ News (@rtenews) December 5, 2019
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Mr Trump "has engaged in abuse of power, undermined our national security and jeopardised the integrity of our elections," she said, adding that "the president leaves us no choice but to act".
Ms Pelosi did not announce the charges, but Mr Trump could face impeachment for bribery, abuse of power, obstruction of Congress and obstruction of justice.
She said that "the president abused his power for his own political benefit at the expense of our national security" by withholding military aid to Ukraine and a White House meeting in exchange for Kiev's commitment to investigate Mr Trump's political rival Joe Biden.
"If we allow a president to be above the law, we do so surely at the peril of our republic," she added.
Mr Trump's chief spokeswoman Stephanie Grisham shot back instantly, saying Democrats should be "ashamed" after pulling the trigger on impeachment.
Democrats reportedly aim to have articles of impeachment presented for a full House vote later this month after weeks of hearings.
They have been building a case that Mr Trump should be impeached for trying to leverage a White House meeting and military aid to pressure Ukraine for dirt on Mr Biden.
Yesterday, three constitutional scholars told the House that the president's actions seeking foreign interference in US elections were clear grounds for removal.
