WASHINGTON - U.S. lawmakers have returned to Washington after their holiday recess, but they are no closer to deciding when and how President Donald Trump will be tried in the Senate on impeachment charges which were approved last month in the House of Representatives.

Key lawmakers remain stalemated over impeachment, now complicated by congressional debate over the merits of Trump's approval of the drone attack that killed a key Iranian general, Qassem Soleimani, last week outside the Baghdad airport.

House Speaker Nancy Pelosi, leader of the Democrat-controlled House, is refusing to send two articles of impeachment to the Senate until she believes it would conduct a fair trial. One article accuses Trump of abusing the power of his presidency to pressure Ukraine to launch an investigation into a key 2020 Democratic rival, former Vice President Joe Biden. The other is regarding obstruction of congressional efforts to investigate his Ukraine-related actions.

Senate Majority Leader Mitch McConnell, leader of the Republican-majority Senate, says his chamber can't hold an impeachment trial without receiving the impeachment allegations from the House, although some Republican senators looking to acquit Trump as quickly as possible now say the Senate should start the trial anyway.

Senate Minority Leader Chuck Schumer has sparred with McConnell to try to win assurances that key Trump White House aides will be allowed to testify at the impeachment trial, which would be only the third in U.S. history.

But McConnell, coordinating legal strategy with Trump's White House lawyers, has balked at guaranteeing that acting White House chief of staff Mick Mulvaney, former national security adviser John Bolton and others would testify.

Schumer said Sunday he remains "hopeful" that four Republican senators will vote against McConnell and join with the minority bloc of 47 Democrats to vote to hear testimony from the Trump aides.

Meanwhile, Trump again ridiculed the impeachment effort on Monday, which was approved with near unanimous Democratic support in the House.

"To be spending time on this political Hoax at this moment in our history, when I am so busy, is sad!" he said on Twitter. 

“The reason they are not sending the Articles of Impeachment to the Senate is that they are so weak and so pathetic.” @LindseyGrahamSC @MariaBartiromo The great Scam continues. To be spending time on this political Hoax at this moment in our history, when I am so busy, is sad!

— Donald J. Trump (@realDonaldTrump) January 6, 2020

He added, "The Impeachment Hoax, just a continuation of the Witch Hunt which started even before I won the Election, must end quickly. Read the Transcripts, see the Ukrainian President’s strong statement, NO PRESSURE - get this done. It is a con game by the Dems to help with the Election!"

"Congress & the President should not be wasting their time and energy on a continuation of the totally partisan Impeachment Hoax when we have so many important matters pending. 196 to ZERO was the Republican House vote, & we got 3 Dems. This was not what the Founders had in mind!"    

Congress & the President should not be wasting their time and energy on a continuation of the totally partisan Impeachment Hoax when we have so many important matters pending. 196 to ZERO was the Republican House vote, & we got 3 Dems. This was not what the Founders had in mind!

— Donald J. Trump (@realDonaldTrump) January 6, 2020

When a trial finally occurs, the Senate will almost certainly acquit Trump.

A two-thirds majority in the 100-member Senate would be required to convict Trump to remove him from office, meaning at least 20 Republicans would have to turn against the president if all 47 Democrats also vote to convict him.

Some Republican lawmakers have voiced objections to Trump's request to Zelenskiy for the investigation of Biden, who leads national polls to oppose Trump in the November presidential election. But no Republican lawmakers have called for Trump's conviction and removal from office.

Trump eventually released the military assistance to Ukraine last September without Zelenskiy opening the Biden investigations. Republicans say that is proof Trump did not engage in a reciprocal quid pro quo deal with Ukraine.

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