Mitch McConnell bridled over Donald Trump's crude governing style but found him a valuable White House ally. Now, the powerful US Senate majority leader controls the outgoing president's political future.

Following Trump's humiliating second impeachment Wednesday, the ever-calculating McConnell has a momentous decision to make: defend the president at all costs and rally his Republicans to prevent Trump's conviction, or work to jettison the contentious and defiant billionaire businessman from Republican politics altogether.

Either way, the 78-year-old senator known for never letting a political crisis go to waste may be more than willing to have a weeks-long impeachment trial overshadow President-elect Joe Biden's early agenda and portray Democrats as going out of their way to exact revenge on Trump.

The seven-term senator from Kentucky held Trump's fate in his hands once before, when the embattled president faced a Senate trial a year ago on impeachment charges of abuse of power and obstruction of Congress.

US Senate Majority Leader Mitch McConnell fiercely defended President Donald Trump in his 2020 impeachment trial, but he has kept his position on this impeachment go around under wraps
US Senate Majority Leader Mitch McConnell fiercely defended President Donald Trump in his 2020 impeachment trial, but he has kept his position on this impeachment go around under wraps AFP / Brendan Smialowski

Trump prevailed, as McConnell held all but one member of his caucus in line to vote against conviction.

McConnell, who has gleefully described himself as the "Grim Reaper" for his ability to kill off Democratic legislation at will, is again the critical link in the impeachment trial process.

But things are different in this second rodeo.

While McConnell was fiercely opposed to the president's removal early last year, backing the White House line that Democrats were on a witch hunt, he said Wednesday he has "not made a final decision" on whether to vote to convict Trump for inciting an insurrection in which a mob of his supporters violently stormed the US Capitol.

US Speaker of the House Nancy Pelosi, a Democrat, led the successful push for impeachment of President Donald Trump, but all eyes are on the Senate's top Republican Mitch McConnell over whether he votes to convict the president
US Speaker of the House Nancy Pelosi, a Democrat, led the successful push for impeachment of President Donald Trump, but all eyes are on the Senate's top Republican Mitch McConnell over whether he votes to convict the president AFP / Brendan SMIALOWSKI

The Senate leader, who already broke with Trump last month over the president's relentless effort to overturn Biden's election win, has hardly been able to contain his disdain for the man in the White House.

The pair sometimes go weeks without speaking, a startling reality given they are the main powerbrokers in the ruling party.

McConnell's wife Elaine Chao served as Trump's transportation secretary, giving the senator invaluable eyes and ears in the White House. But she resigned in disgust after the Capitol violence.

US Senate Majority Leader Mitch McConnell, seen with his wife Elaine Chao, the former secretary of transportation, at a mock swearing in on January 3, 2021 for his seventh term as a US senator
US Senate Majority Leader Mitch McConnell, seen with his wife Elaine Chao, the former secretary of transportation, at a mock swearing in on January 3, 2021 for his seventh term as a US senator POOL / Samuel Corum

And in an explosive story Tuesday citing people familiar with McConnell's thinking, the New York Times reported that the leader has privately concluded Trump committed impeachable offenses, and that the Democrats' push to impeach would facilitate Trump's banishment from the party.

Such leaks rarely occur by accident in Washington, and word is that McConnell, believing Trump has outlived his usefulness in cementing a conservative track for the nation, may be positioning himself for washing his hands of Trump altogether.

That opens the door for other Republicans in the Senate, many of whom take their cue from McConnell, to break with Trump.

If 17 of them do, Trump would become the first president ever convicted of impeachment charges. A follow-up vote would ban him from future public office.

The trial, however, will not happen on McConnell's watch. Democrats will control the Senate once Biden takes office on January 20, after Republicans lost two seats in runoff races this month in Georgia, where anti-Trump sentiment fueled a record Democratic turnout.

And McConnell has refused to bring his chamber back into session early to allow the trial to kick off before Inauguration Day, meaning Trump will be tried as a former president.

That said, Trump has been a godsend for McConnell's efforts to reshape the federal judiciary.

The president has nominated, and McConnell's Senate has confirmed, three conservative Supreme Court justices, as well as 229 judges to federal benches, a modern day record for a single term.

And it was McConnell's clamor over the judiciary -- he defied president Barack Obama and refused to consider his Supreme Court nominee in an election year -- that many say led to Trump's shock 2016 win.

Trump also pleased McConnell by ramming through a massive $2 trillion tax cut that benefited corporations and the wealthy.

So what is McConnell's play in the coming weeks? One option could be to publicly not oppose the trial, all the while knowing that Trump is unlikely to be convicted.

McConnell is no doubt aware that the trial could gum up Biden's effort to shift the narrative to his pandemic relief and economic rescue plans.

And a second straight Trump acquittal may well strengthen Republicans heading into all-important 2022 midterm elections -- although the party is facing a major internal debate over whether to embrace Trumpism or walk away.