After four years of moving in virtual lockstep with Donald Trump, Mitch McConnell used his final day as Senate majority leader to make a clean break with the outgoing president.

In a speech on the Senate floor on the eve of Joe Biden’s inauguration, McConnell, the chamber’s top Republican, placed the blame for the violent January 6 siege on the Capitol squarely on Trump.

“The mob was fed lies. They were provoked by the president and other powerful people,” McConnell said. “And they tried to use fear and violence to stop a specific proceeding of the first branch of the federal government which they did not like.”

The comments sent shockwaves through a Washington that had just seen the House of Representatives impeach Trump for a second time. They fuelled speculation that the Kentucky senator might vote to convict Trump of inciting an insurrection — seizing the opportunity of a Senate trial to bar him from public office and rid the Republican party of the former president.

Yet with the Senate trial due to begin this week, McConnell is striking a very different tone. Just one week after blaming Trump for the riots, he joined 44 fellow Republicans in backing a Senate motion declaring an impeachment trial unconstitutional because Trump is no longer in the White House.

The motion failed to scupper a trial because five Republicans sided with the Democrats, who now control the upper chamber of Congress, in opposing the measure.

But it sent a clear signal that Trump’s impeachment trial, which is set to start on Tuesday, will probably result in his exoneration. Under the US constitution, conviction requires the support of two-thirds of the 100-member chamber, or at least 17 Republicans in the current Congress.

“It is one of the few times in Washington where a loss is actually a victory,” Rand Paul, the other Republican senator from Kentucky, said after the procedural vote. “Forty-five votes means the impeachment trial is dead on arrival.”

Some of the former president’s Republican critics hoped the traumatic scenes of a mob of Trump supporters ransacking the Capitol — after months of his false claims that November’s presidential election was “stolen” and refusals to concede defeat to Biden — might finally persuade the rest of the party to see him as a malign influence.

Hours before the mob of his supporters stormed the legislature, leaving five people dead, Trump told the crowd: “If you don’t fight like hell, you’re not going to have a country any more.”

But Trump’s opponents and supporters alike say the preliminary vote in the Senate underscores just how much influence the former president still has over the party in Washington, even after being banned from all major social media platforms, snubbing Biden’s inauguration and retreating to his Mar-a-Lago resort in Florida.

“There is no evidence that base Republican voters saw what happened [on January 6], and feel like Donald Trump deserves any punishment for it,” says Brendan Buck, a former aide to Republican House speakers Paul Ryan and John Boehner, and frequent Trump critic. “That is what senators are reflecting: their voters.”

A Monmouth University poll published last week showed that while a clear majority of American voters supported Trump being impeached, just 13 per cent of Republicans were in favour of impeachment, compared with 92 per cent of Democrats and 52 per cent of independents.

“The Republican party is the party of Donald John Trump for the foreseeable future,” says Ford O’Connell, a former Republican congressional candidate in Florida and a Trump ally. “The base of the Republican party loves Trump, and the base has that power over elected officials in Washington.”

Trump was impeached, or charged, for inciting an insurrection in a bipartisan House vote last month, with 10 Republican members, including Liz Cheney, a senior Republican and the daughter of George W Bush’s vice-president Dick Cheney, joining the entire Democratic caucus.

The bipartisan nature of the impeachment vote was significant, given no Republicans backed Trump’s first impeachment, in 2019, for his efforts to pressure the Ukrainian president to dig up dirt on Biden and his family. But it also exposed how few elected Republicans have the stomach to stand up to Trump at a time when so many of their voters are still enamoured with him.

“January 6 was the opening battle in the war for the soul of the Republican party,” says Whit Ayres, a veteran GOP pollster. “The GOP is seriously split into a governing faction and a populist faction . . . the populist faction is not going away even if Donald Trump does.”

Democrats took back control of the Senate on inauguration day, after the swearing-in of Democrats Raphael Warnock and Jon Ossoff who won two hotly contested run-offs in Georgia.

That demoted McConnell, 78, to the position of Senate minority leader, where he will effectively act as leader of the opposition until Republicans have a run at reclaiming both chambers of Congress in the 2022 midterm elections.

Allies describe McConnell’s approach to the impeachment trial and the cleavages in the Republican party as playing the “long game” — which, perhaps in no coincidence, is the title of the Kentucky senator’s 2016 memoir.

They say the minority leader is seeking to forge a middle path that will keep Trump’s fervent base of supporters onside while at the same time appealing to the more moderate voters, particularly in America’s suburbs, who turned their back on the GOP over the former president’s bombastic rhetoric. Their votes proved hugely consequential both in November’s presidential election and the two Senate run-offs in January in Georgia that cost Republicans their majority.

In his final days in office, Trump briefly toyed with the possibility of forming a “Patriot party”. But his allies now say the president has gone off the idea, given the US system makes third parties exceedingly unlikely to succeed at the national level.

“The idea of a third party, while it sounds enticing in theory, in practicality it is a disaster,” says O’Connell. “It is the quickest way to make sure that you never get to power again.”

McConnell will also be looking to win back support from corporate America, after many companies pulled their campaign donations over Trump’s role in the January 6 siege and have broadly supported Biden’s calls for a return to bipartisanship and civility in government.

“Senator McConnell has the position and power and respect that he has because he is very smart,” says Antonia Ferrier, a former senior aide to the minority leader. “He understands and appreciates that Republican base voters matter . . . but you ultimately have to find that right balance whereby you are getting your base voters to go out and vote, and you are not alienating suburban voters.”

McConnell, who was first elected to the Senate nearly four decades ago, last week took the rare step of intervening in not one but two debates embroiling House Republicans and illustrating the party’s infighting.

First, McConnell issued a scathing statement in reference to Marjorie Taylor Greene, the freshman Georgia congresswoman who has attracted ire for her previous statements in support of conspiracy theories, including that deadly school shootings that killed dozens of children in Newtown, Connecticut, and Parkland, Florida, were “false flags” set up by Democrats to impose stricter gun laws.“Somebody who’s suggested that perhaps no aeroplane hit the Pentagon on 9/11, that horrifying school shootings were pre-staged, and that the Clintons crashed JFK Jr’s aeroplane is not living in reality,” McConnell said in a statement to The Hill newspaper, calling “loony lies and conspiracy theories” a “cancer” on the party.

Soon after, the Senate minority leader voiced his support for Cheney, who faced calls from fellow Republicans for her to be removed from leadership over her vote to impeach the president. Matt Gaetz, the Republican congressman from Florida and fierce Trump ally, flew to Cheney’s district in Wyoming and held a rally railing against his colleague and calling for her to be challenged in a Republican primary. Opinion polling in the state shows the congresswoman’s approval ratings have fallen sharply since the vote.

McConnell issued a statement calling Cheney a “leader with deep convictions and the courage to act on them”, adding: “She is an important leader in our party and in our nation.”

Cheney, who holds the title of House Republican conference chair, survived a confidence vote last week with the support of 145 of her Republican colleagues. Sixty-one GOP House members voted in favour of her being ousted — a number many in Washington believe would have been higher had the ballot not been carried out in secret.

The interventions put McConnell out of step with his House counterpart, Kevin McCarthy.

A Republican lawmaker from California, McCarthy, 56, was an unflinching supporter of Trump throughout his presidency. He wavered slightly in the days following the January 6 siege, saying the former president “bears responsibility” for the carnage.

But within weeks, the House minority leader was back in Trump’s good graces, flying down to Palm Beach for a photo op in an ornate room at Mar-a-Lago.

“House Republicans and the Trump administration achieved historic results for all Americans,” McCarthy said in a statement after the meeting. “House Republicans defied the experts and the media by expanding our growing coalition across the country.”

While Republicans lost the White House and the Senate on November 3, they improved their margins in the House, picking up several seats and narrowing Nancy Pelosi and the Democrats’ majority. Many Republican operatives argue this puts the lower chamber of Congress within the party’s grasp for the 2022 midterms — and reinforces that they should continue with the same messages rather than reinvent their playbook.

McCarthy made clear he sees Trump as part of the winning formula, saying the former president “committed to helping elect Republicans”, and adding: “A united conservative movement will strengthen the bonds of our citizens and uphold the freedoms our country was founded on.”

Buck says McCarthy made a decision that in order to lead the conference, he needed to be “all in” with Trump: “He obviously flirted with moving away from him a bit, and I think has learnt and seen with the example of Liz Cheney, that his position is not strong enough to be able to both be apart from Trump and to top the conference.”

McCarthy last week made clear that he saw House Republicans as a broad church with room for the likes of Cheney and Greene. He encouraged colleagues to back Cheney’s leadership position, but also rejected Democrats’ demands for him to strip Greene of her committee assignments — something Democrats later did on their own, with the support of 11 Republicans.

GOP pollster Frank Luntz defends McCarthy’s efforts, saying: “Kevin McCarthy is trying to look forward and trying to seek some sort of accommodation with a party that is horrifically broken.”

But a handful of members of McCarthy’s own caucus disagree about the path forward. Chief among them is Adam Kinzinger, a 42-year-old conservative House member from Illinois who was first elected to Congress in 2010 on a wave of support for the populist Tea Party movement.

Yet Kinzinger saw January 6 as a turning point, and joined Cheney and eight other House Republicans in voting to impeach. Last week, he launched a political action committee, or fundraising vehicle, called Country First to support anti-Trump Republicans and purge the party of the former president’s influence.

“There really is a desire for people to both speak out, to have somebody speak out, and be part of fighting for the future of the party, instead of just accepting that it is going where it is going,” he says, adding he has been encouraged by the early swell of support.

Kinzinger seems optimistic that more Republicans will join him, though few of his House colleagues have put their heads above the parapet.

“There has been a culture of fear in the party, still. When it comes to speaking out, every time people have spoken out against President Trump, they get hit down,” he says. “I think there are a lot of people rooting for it but just are not comfortable taking that position.”

An Iraq war veteran, he likewise seems at peace with the possibility that his actions could see him ousted from office as soon as next year by a pro-Trump Republican in a primary, saying: “We applaud people that are willing to die for their country, but we are not willing to give up our career.”

Kinzinger is nevertheless frank about the challenges facing his party — and the possibility that there may no longer be room for people like him in the GOP.

“Quite honestly, you have to ask if the party keeps going in this direction, ‘is it my party?’” he says. “Is our loyalty to the constitution or is it to a man? I think that is really what the question is for the party.”