Trump's blistering letter to Pelosi: Five key quotes

Donald Trump has some words for House Speaker Nancy Pelosi and the rest of the congressional Democrats on the eve of his impeachment. Over six pages, on White House letterhead, the president piles adjectives like cords of wood, fires rhetorical fusillades in all directions and invokes the judgement of the American people, the nation's founding fathers and history itself.

It's a presidential airing of grievances six days before Festivus (that mythical rage-fuelled holiday immortalised by the TV show Seinfeld).

Here are five choice lines from a president whose capacity for the extraordinary and unprecedented is ever-expanding.

• Read the letter

• A bumpy ride for Democrat backing impeachment

• Rudy Giuliani 'forced Ukraine ambassador out'

"You have cheapened the importance of the very ugly word, impeachment!"

Donald Trump's defenders have warned that Democrats are lowering the bar for impeachment and inviting a future in which the process is used by House majorities to bully and bedevil a president of an opposing party. That's the gist of what Trump is saying here, although suggesting one can "cheapen" an already "ugly" word is an interesting take.

"Even worse than offending the Founding Fathers, you are offending Americans of faith by continually saying 'I pray for the president', when you know this statement is not true, unless it is meant in the negative sense."

Nancy Pelosi's temper flared a few weeks ago when a conservative journalist suggested that she hated the president. The House speaker, a practising Catholic, has frequently referred to her faith as a guide and said that, while she is acting against the president's interests, she does so with remorse, not vindictiveness. Trump - who rarely practises and seldom talks of his religion - wants everyone to know he thinks Pelosi's assertions are bunk.

"You are turning a policy disagreement between two branches of government into an impeachable offence - it is no more legitimate than the Executive Branch charging members of Congress with crimes for lawful exercise of legislative power."

This sounds like a threat. Is it a threat? The process of impeachment was designed by the American founders to be a component of the checks-and-balances system that created tension between the executive and legislative branches of government. (The third branch, the judiciary, will have its own role to play, as the chief justice oversees a presidential trial in the Senate following impeachment.)

The founders left the grounds for what constituted an impeachable offence relatively open and undefined. It is what a majority of the House says it is, and its legitimacy is derived from the will of that majority.

"You know full well that Vice President Joe Biden used his office and $1bn of US aid money to coerce Ukraine into firing the prosecutor who was digging into the company paying his son millions of dollars."

While Biden, now a Democratic candidate for president, did pressure Ukraine to fire its top prosecutor and even bragged about it in the video Trump references, the prosecutor was not actively investigating the company on whose board Biden's son served.

What's more, Biden was acting at the behest of the Obama administration, other Western governments and Ukrainian government reformers, who viewed the prosecutor as corrupt. Biden has been criticised for an appearance of a conflict of interest because of his son's Ukraine ties - there has been no evidence of misconduct by the then-vice-president.

"I write this letter to you for the purpose of history and to put my thoughts on a permanent and indelible record. One hundred years from now, when people look back at this affair, I want them to understand it, and learn from it, so that it can never happen to another president again."

The last few pages of Trump's letters are a collection of allegations against Democrats, the FBI and the impeachment process, along with a 214-word sentence boasting of his presidential accomplishments. His concluding lines, however, reveal the reason for this most unorthodox letter.

At the White House on Tuesday President Trump said that impeachment was a disgrace and a "mark on our country". With his six-page letter, he sounds more concerned that it will be a mark on his presidency.

The man who regularly heralds his three years in office as the greatest, the most successful, the most extraordinary reign of any American chief executive will now have to explain why he is only the third president to face a Senate trial with his tenure in office at stake.