US PRESIDENT Donald Trump said today he would boycott an impeachment inquiry against him, rejecting it as illegitimate and a violation of the constitution.

In a letter sent to Democratic Party leaders, Mr Trump warned that the proceedings against him were “baseless” and violated “fundamental fairness and constitutionally mandated due process.”

The White House letter complained that Mr Trump was being denied the right to cross-examine witnesses, to call witnesses “and many other basic rights guaranteed to all Americans.”

The Democrats were accused of wanting to overturn the result of the 2016 election “and deprive the American people of the president they have freely chosen.”

The letter argued that further than this, the Democrats were using the impeachment process to influence the 2020 election by inflicting damage on Mr Trump.

“Never before in our history has the House of Representatives — under the control of either political party — taken the American people down the dangerous path you seem determined to pursue,” it read.

Three Democratic-led House committees are investigating Mr Trump’s actions in an attempt to discover whether he withheld aid to Ukraine in a bid to force it to investigate his potential presidential rival Joe Biden.

The former vice-president is accused of pressing for the sacking of Ukraine’s top prosecutor Viktor Shokin who was investigating corruption in the gas holdings group Burisma of which his son, Hunter, was a director.

Mr Biden is believed to have threatened to withhold aid from Ukraine unless the dismissal was made.

Senior Democrat Nancy Pelosi branded the letter “manifestly wrong” and accused Mr Trump of trying to “normalise lawlessness.”

“Mr President, you are not above the law. You will be held accountable,” she said.