WASHINGTON — A Senate still bruised from the most violent attack on the Capitol in two centuries acquitted former President Donald J. Trump on Saturday in his second impeachment trial, as all but a few Republicans locked arms to reject a case that he incited the Jan. 6 rampage in a last-ditch attempt to cling to power.

Under the watch of National Guard troops still patrolling the historic building, a bipartisan majority cast votes finding Mr. Trump guilty of the House’s single charge of “incitement of insurrection.” They included seven Republicans, more members of a president’s party than have ever returned an adverse verdict in an impeachment trial.

But with most of Mr. Trump’s party coalescing around him, the 57-to-43 tally fell 10 votes short of the two-thirds majority needed to convict, and allow the Senate to move to disqualify him from holding future office.

Among the Republicans breaking ranks to find guilty the man who led their party for four tumultuous years, demanding absolute loyalty, were Senators Richard Burr of North Carolina, Bill Cassidy of Louisiana, Susan Collins of Maine, Lisa Murkowski of Alaska, Mitt Romney of Utah, Ben Sasse of Nebraska and Patrick J. Toomey of Pennsylvania.

The verdict brought an abrupt end to the fourth presidential impeachment trial in American history, and the only one in which the accused had left office before being tried. But it was unlikely to be the final word for Mr. Trump, his badly divided party or the sprawling criminal and congressional investigations into the assault.

It left behind festering wounds in Washington and around the country after a 39-day stretch unlike any in the nation’s history — encompassing a deadly riot at the Capitol, an impeachment of one president, the inauguration of another and a brief but rancorous trial in the Senate.