President Donald Trump’s unprecedented second impeachment heads to the Senate, where his fate rests with Republican leader Mitch McConnell, who now has more leverage than ever over the president in his final week in office.McConnell told Republican colleagues in a letter Wednesday he would block starting an impeachment trial before Joe Biden takes office Jan. 20 and control of the Senate shifts to Democrats.

But he also said he has not yet made up his mind on whether to vote to convict Trump of inciting an insurrection that left five dead and damaged the Capitol, including the Senate chamber where he has spent much of the past 36 years.

That allows Trump to finish his term without being removed from office. But McConnell has left open the option that if Trump were to instigate more unrest or take any other dangerous action, he could turn against him. That would raise the odds there would be enough Republican votes for Trump’s conviction and a possible ban on ever again serving in office.

The next steps after Wednesday’s House impeachment vote depend on how McConnell, House Speaker Nancy Pelosi and Senate Democratic leader Chuck Schumer navigate the politics of a trial, a change of administration and a shift in power in the Senate all happening simultaneously.

Much is uncertain, but one thing is clear: the Senate isn’t back until Jan. 19, so no trial can start before Jan. 20 -- the same day Biden is sworn in -- under McConnell’s timeline.

Pelosi hasn’t said publicly when she’ll send the article of impeachment to the Senate. Once she does, an intricate and prescribed process for the trial plays out.

Most significantly, all other business grinds to a halt unless all 100 senators agree to conduct any other work. That could mean no confirmation votes for Biden’s nominees or votes on early legislative initiatives, raising the prospect that he could start his administration without key cabinet secretaries in place.

Biden has been exploring with leaders whether there might be a bipartisan pact to split the Senate days between regular business -- such as confirmation votes -- and the trial. There has not been any sign yet of a resolution, though committees are proceeding with hearings on Jan. 19 for Treasury, State, Defense and Homeland Security posts.

“This nation also remains in the grip of a deadly virus and a reeling economy,” Biden said in a statement Wednesday. “I hope that the Senate leadership will find a way to deal with their constitutional responsibilities on impeachment while also working on the other urgent business of this nation.”

Also left to be negotiated are the details of the trial, such as length and scope of the process, whether to subpoena documents and witnesses.

Impeachment managers from the House would serve as prosecutors and Trump would be allowed to mount a defense.

It’s not even clear whether Chief Justice John Roberts would preside over a trial of a former president, something that’s never happened before in history and could face legal challenges as well.

Trump’s impeachment trial a year ago lasted almost three weeks. But the evidence from Democrats this time primarily consists of videos of Trump’s own statements and the subsequent actions of the crowd. That’s suggests a shorter proceeding.

Once two Senate contests are certified in Georgia and Vice President-elect Kamala Harris is sworn in -- giving her the tie breaking vote in a 50-50 Senate -- Schumer will take over from McConnell as majority leader. Yet even in minority status, McConnell will have some say over the conduct of the trial with an evenly divided Senate..

McConnell’s delay in beginning any trial hands the newly empowered Democrats a dilemma — the longer they spend prosecuting the case against Trump, the less time they’ll have to move priority pieces of Biden’s agenda.

Trump himself tried to appeal to Republican holdouts with multiple statements Wednesday opposing violence and disavowing the mob that stormed the Capitol on his behalf.

“I unequivocally condemn the violence that we saw last week,” Trump said in a video released by the White House. “Now I am asking everyone who has ever believed in our agenda to be thinking of ways to ease tensions, calm tempers and help to promote peace in our country.”

Senator Lindsey Graham, a South Carolina Republican who has staunchly defended Trump over the past four years, used that statement to argue that Trump is helping move the country forward. In a series of tweets Wednesday evening he appealed to Biden “to rise to the occasion and instruct his party to call off post-presidential impeachment proceedings.”

He also praised Trump’s statement, calling on Americans to avoid further violence, in a video released by the White House after the impeachment vote.

McConnell’s Influence

While 10 House Republicans joined Democrats in the 232-197 vote to impeach Trump, what McConnell does next could have enormous influence in a chamber where no GOP senators have said yet that they would convict him.

It would take 67 votes to convict Trump and mete the only real punishment to a president who would have just left office -- a bar on future runs for office -- and the chamber will be split 50-50 between the two parties.

McConnell has told associates he considers Trump’s conduct surrounding the riot to be impeachable, according to two sources, putting Trump in the danger zone. A handful of others have sharply criticized Trump’s actions, including Ben Sasse of Nebraska, Mitt Romney of Utah, Susan Collins of Maine, Lisa Murkowski of Alaska and Pat Toomey of Pennsylvania.

Without cover from McConnell, there’s little expectation most Republicans would risk convicting an ex-president who remains popular among the Republican Party base.

Romney was the only Republican to vote for conviction on one count during Trump’s impeachment trial in January 2020, though the timing of that trial came when many Republicans, including McConnell, were heading into an election year.

There is little Trump can do to McConnell politically now. While his allies threatened Republicans who didn’t vote to overturn the election, let alone impeach Trump, with primaries, McConnell doesn’t face the voters in Kentucky again until 2026, if he even runs then.

His position leading the Senate GOP — he’s already the longest serving Republican leader in history — is unchallenged.

Many other McConnell allies haven’t ruled out impeachment and aren’t up until 2024 or 2026 either, somewhat insulating them from the wrath of Trump loyalists.