The Capitol Hill is shrouded in fog in Washington D.C., the United States, on Dec. 17, 2019. U.S. President Donald Trump on Tuesday sent a six-page letter to House Speaker Nancy Pelosi, slamming the House Democrats impeachment effort as an "illegal, partisan attempted coup" and an "unprecedented and unconstitutional abuse of power." (Xinhua/Liu Jie)

U.S. President Donald Trump on Tuesday sent a six-page letter to House Speaker Nancy Pelosi, slamming the House Democrats impeachment effort as an "illegal, partisan attempted coup" and an "unprecedented and unconstitutional abuse of power."

"It is time for you and the highly partisan Democrats in Congress to immediately cease this impeachment fantasy and get back to work for the American People," Trump wrote, adding that he has "no expectation" that House Democrats will do so.

The Capitol Hill is shrouded in fog in Washington D.C., the United States, on Dec. 17, 2019. U.S. President Donald Trump on Tuesday sent a six-page letter to House Speaker Nancy Pelosi, slamming the House Democrats impeachment effort as an "illegal, partisan attempted coup" and an "unprecedented and unconstitutional abuse of power." (Xinhua/Liu Jie)

 
In the letter, Trump defended his conduct toward Ukraine, accusing Democrats of "interfering in America's elections."

"You are the ones interfering in America's elections. You are the ones subverting America's Democracy. You are the ones Obstructing Justice," Trump wrote to Pelosi. "You are the ones bringing pain and suffering to our Republic for your own selfish personal, political, and partisan gain."

Moments after the letter was publicized, the president said in the White House that he takes "zero" responsibility for facing impeachment.

The Capitol Hill is shrouded in fog in Washington D.C., the United States, on Dec. 17, 2019. U.S. President Donald Trump on Tuesday sent a six-page letter to House Speaker Nancy Pelosi, slamming the House Democrats impeachment effort as an "illegal, partisan attempted coup" and an "unprecedented and unconstitutional abuse of power." (Xinhua/Liu Jie)

 
The Democrat-led House is poised to vote on Wednesday on two articles of impeachment accusing Trump of abusing power and obstruction of Congress. If any of the two articles is approved, Trump will be the third president in the U.S. history to be formally impeached and face a trial in the Senate.

Thereafter, the articles would move to a trial in the Republican-controlled Senate where Trump is widely expected to be acquitted.

House Democrats have accused Trump of abusing his office by pressuring Ukraine to pursue investigations that could benefit his reelection campaign. The White House has refused to cooperate in the impeachment inquiry, accusing Democrats of an unfair process that aims to overturn the results of the 2016 election.

The Capitol Hill is shrouded in fog in Washington D.C., the United States, on Dec. 17, 2019. U.S. President Donald Trump on Tuesday sent a six-page letter to House Speaker Nancy Pelosi, slamming the House Democrats impeachment effort as an "illegal, partisan attempted coup" and an "unprecedented and unconstitutional abuse of power." (Xinhua/Liu Jie)

 
Under the U.S. constitution, the House shall have the sole power of impeachment while the Senate shall have the sole power to try all impeachments.

Conviction can only happen in the Senate and requires at least two-thirds of its members, or 67 senators, to vote in favor after a trial. Currently, the Senate has 53 Republicans, 45 Democrats and two independents.