A day after Donald J. Trump’s conviction, it quickly became clear that Republicans across the country would not run away from his newfound status as a felon.

They would, instead, run on it.

Echoing Mr. Trump in casting the New York case as a disgraceful sham, Republican candidates and party committees used the first criminal conviction of a former president as a rallying cry — for campaign cash, for congressional hearings and for motivation to vote in November.

Whether they were congressional leaders, potential running mates or onetime rivals, prominent Republicans’ speedy alignment behind Mr. Trump, with little dissent or discussion, was no surprise for a party that has increasingly made displays of Trumpian loyalty a nonnegotiable requirement. But their ready-made outrage was not just about lining up behind the nominee. It was also about basking in the energy of a party base that remains as adhered to Mr. Trump as ever.

“The base has never been more motivated,” said Representative Ronny Jackson of Texas, Mr. Trump’s former doctor in the White House and a close ally.

In a 33-minute speech in the same Trump Tower lobby where he began his first presidential bid nearly nine years ago, Mr. Trump denounced his prosecutors as “sick people” on Friday and criticized the key witness in the case, seeking to pivot his candidacy from the confines of a Manhattan courtroom to the campaign trail.

The Trump campaign’s announcement on Friday morning that it had raised $34.8 million online in the hours after a jury found Mr. Trump guilty on all 34 felony charges was a reminder of how thoroughly he has persuaded Republican voters that his own legal threats are a proxy for attacks on them.