A single juror prevented former Illinois Governor Rod Blagojevich being convicted of selling Barack Obama's Senate seat, the jury foreman has said.
The juror, a female retiree, believed there wasn't sufficient evidence - "a smoking gun" - to warrant a conviction for corruption, James Matsumoto said.
"She saw it as, no crime was being committed. It was just talk - political talk," Mr Matsumoto told reporters.
The Chicago federal jury convicted Blagojevich of lying to FBI agents.
That charge carries a maximum sentence of five years in jail.
The jury was unable to reach unanimous verdicts on 23 other corruption charges. On several charges, the same juror held out.
The verdict came on the jury's 14th day of deliberations. Mr Matsumoto said the jury room was often tense.
Another juror, Erik Sarnello, told the Chicago Sun-Times newspaper that some jurors found the government's case - which involved several different instances of alleged corruption over many years - to be confusing.
The jury was split different ways on each charge, sometimes 6-6, other times 9-3. But in the end, the most explosive charge - seeking to sell Mr Obama's senate seat - came down to one person.
"Say it was a murder trial - she wanted the video," the Chicago Sun-Times reports Mr Sarnello as saying.
"She wanted to hear [Blagojevich] say, 'I'll give you this for that'.
"For some people, it was clear. Some people heard that. But for some, it wasn't clear.''
After the verdict was announced, US attorneys said the government planned to retry the case "as quickly as possible".
Speaking afterwards outside the court, Mr Blagojevich, 53, was defiant.
"This jury shows you that the government threw everything but the kitchen sink at me," he said.
"They could not prove I did anything wrong - except for one nebulous charge from five years ago."
His lawyer said he would appeal against the conviction.
The judge said he intended to declare a mistrial on the remaining counts and retrial hearings will commence on 26 August.
The one charge on which Blagojevich was found guilty was that he lied to federal agents when he said he did not track campaign contributions and that he kept a "firewall" between his political campaigns and his government work.
The case involved hours of conversations wire-tapped by the FBI.
Defence lawyers had maintained that Blagojevich's talk was mere bluster and he had done nothing illegal.
Blagojevich, a Democrat, was ejected from office by the Illinois state legislature in January 2009.