A day after the Senate acquitted Donald Trump in a historic second impeachment trial, America was weighing how long a shadow the former president, even with a tarnished legacy, will continue to cast — over his party, and over the country.

As much of the world watched, the Senate on Saturday voted 57-43 to convict Trump of inciting the January 6 assault on the US Capitol.

It was a stinging rebuke, with seven Republicans joining all Democrats in the most bipartisan impeachment vote ever, but it fell short of the 67 votes needed for conviction.

With Trump hinting afterward at a possible political future even as other Republicans said it was time to move on, the stark divide facing the party over the deeply controversial ex-president was on full view.

One frequent Trump critic, Governor Larry Hogan of Maryland, on Sunday predicted a "real battle for the soul of the Republican Party".

"This is not over," the Republican governor told CNN, adding he would have voted to convict Trump.

Senator Bill Cassidy of Louisiana was one of the seven Republicans to vote to convict; he predicted Sunday that Trump's still-strong hold on Republicans would fade.

"I think his force wanes. The Republican Party is more than just one person... I think our leadership will be different going forward,” he told ABC’s "This Week”.

Several Republicans, even while voting to acquit Trump, expressed dismay over his role on January 6 and in the weeks before as he stoked anger with false claims the November election was stolen from him.

But one of the former president’s fiercest defenders, Senator Lindsey Graham of South Carolina, insisted on Sunday that Trump, with his fervent following, retains a huge political role as the party looks ahead to the 2022 midterm elections.

He called Trump the "most vibrant member of the Republican Party”, adding, "We need Trump-Plus in 2022.”

Unknowns ahead 

Trump has flirted with the idea of running for the White House again in 2024. A conviction on Saturday would have likely barred him from holding federal office again.

Merely hinting at a possible run will keep him in political conversations — and allow him to continue raising large amounts of money.

A number of Republicans have distanced themselves from the former president — 10 Republican members of the House voted for impeachment — and several who are lining up to seek the presidential nomination in 2024 will be eager to leave him in the party’s past.

But Republicans who have openly opposed Trump have faced fierce blowbacks from the party’s base, and many remain fearful of his continuing hold — and of his tendency to exact payback from critics.

Trump faces a long list of unknowns going forward.

He has lost the megaphone that Twitter once provided him. It is unclear whether he will again organise the big, boisterous rallies he has thrived upon, and if so, whether they will reach the same raucous levels of enthusiasm.

And Senate Republican leader Mitch McConnell — who voted against conviction, saying a former president could not be impeached — on Saturday identified another major challenge facing Trump.

In a blistering attack from the Senate floor just after the vote, McConnell said "there’s no question — none — that President Trump is practically and morally responsible for provoking the events” of January 6.

He stressed that Trump, as a civilian now, faces legal vulnerability on a range of issues — from tax questions raised by his vast financial holdings to sexual assault accusations — and added: "He didn’t get away with anything yet.”

Democrats lashed out at McConnell for launching into such criticism only after voting to acquit.

Still, as the party’s de facto leader, McConnell seemed determined to quash any future political role for Trump and begin guiding Republicans back in a more traditional direction.

Trump has been secluded in his Florida club since leaving office on January 20.

In his statement Saturday, he welcomed the verdict, denouncing the proceedings as "yet another phase of the greatest witch hunt in the history of our country”.

He then added: "We have so much work ahead of us, and soon we will emerge with a vision for a bright, radiant and limitless American future.”