“The sense around here is it’s going to take some time to restore the public trust in elected officials,” said David Toscano, the minority leader of the House of Delegates.

“You could probably have drawn a circle around Capitol Square for a mile and not found three people who would have predicted the outcome,” said Quentin Kidd, a political scientist and pollster at Christopher Newport University in Newport News, who speaks often to state lawmakers and journalists. “The jury didn’t see any gray area. They said this is just flat-out wrong.”

Judge James R. Spencer, who set a sentencing hearing for Jan. 6, will be guided by rules that take account of prior convictions, character witnesses and length of public service. “It looks to me like the government will call for a sentence of about eight to 10 years” for Mr. McDonnell, said Randall Eliason, a former head of the public corruption unit in the United States attorney’s office in Washington. Ms. McDonnell, he predicted, will face less time because she was not a public official.

Legal experts said the most likely avenue for an appeal, which lawyers for the McDonnells promised after the convictions on Thursday, was on Judge Spencer’s instructions to jurors broadly defining an “official act” by the governor. The issue of guilt on four bribery charges turned on whether, in exchange for the McDonnells’ taking Mr. Williams’s largess, the governor performed official acts for him. The defense claimed that Mr. McDonnell offered only trivial courtesies like introducing Mr. Williams to state officials and allowing him access to the Executive Mansion for a promotional lunch. The judge told jurors that an official act was any that a governor “customarily performs,” even if it is not spelled out in the state’s statutes.

“I think this instruction pretty much doomed McDonnell,” said Andrew G. McBride, a former prosecutor in the same Richmond office that brought the charges, adding, “I think they have a substantial case on appeal. They have an appeal to say that was way overbroad.”

There is an energetic debate in appellate courts over what constitutes an official act in bribery cases. “I personally think the judge got it right,” said Mr. Eliason, who teaches white-collar criminal law at George Washington University Law School.

An appeal would push the McDonnells back from reporting to prison for a year or more, assuming Judge Spencer decides they are not flight risks and allows them to remain free on bond.