WASHINGTON -- The trial of Roger Stone, the flamboyant former confidant of President Donald Trump, kicked off Tuesday amid a host of medical issues involving both the defendant and a spectator.

Shortly after jury selection began, the courtroom had to be cleared for more than a half hour when a man sitting in the back row moaned loudly and collapsed on the floor. He was revived and helped from the room by medical staff. Not long after the session resumed, Stone himself went home early, telling U.S. District Judge Amy Berman Jackson that he had food poisoning.

Stone, a longtime Republican provocateur, faces charges related to allegations he sought to collaborate with WikiLeaks to release emails hacked by Russia to damage Hillary Clinton's Democratic presidential campaign.

The trial in Washington promises to revive the spectre of special counsel Robert Mueller's investigation as the impeachment inquiry against Trump proceeds in the House. Stone's indictment in January stems directly from Mueller's investigation. He is accused of lying to lawmakers about WikiLeaks, tampering with witnesses and obstructing a House Intelligence Committee probe into whether the Trump campaign co-ordinated with Russia to tip the 2016 election.

Stone, whose history in Republican political circles dates back to the Nixon administration, has consistently criticized the case against him as politically motivated. Day One was focused on jury selection and featured some of the political complexities that may dominate the case.

Jackson started the day by fending off attempts by the defence team to exclude any potential jurors who worked in the U.S. government or had a negative view of Trump. Berman pointed out that excluding all government workers may be impossible given the nature of the District of Columbia jury pool.

Sure enough, the first potential juror was a woman who had worked in the Office of Management and Budget in the Obama White House and whose husband is a lawyer in the Department of Justice.

Jackson also rejected the notion that a juror who was opposed to Trump would not be fair to Stone.

"That doesn't mean the juror is biased against THIS defendant on THESE charges," Jackson told defence attorneys. "The defence has assumed bias that has not been shown on the part of those people."

Stone, a longtime friend of the president's, briefly served on Trump's campaign but was pushed out amid infighting with campaign manager Corey Lewandowski. Though sidelined, he continued to communicate with Trump and stayed plugged into his circle of advisers.

The indictment says Stone, who was arrested by the FBI in a raid at his Florida home, repeatedly discussed WikiLeaks in 2016 with campaign associates and lays out in detail Stone's conversations about emails stolen from Clinton campaign chairman John Podesta and posted in the weeks before Trump beat Clinton.

After WikiLeaks released hacked emails from the Democratic National Committee on July 22, 2016, the indictment says, a senior Trump campaign official "was directed" to contact Stone about additional releases and about "what other damaging information" WikiLeaks had "regarding the Clinton campaign." The indictment does not name the official or say who directed the outreach to Stone.

Stone is also accused of threatening New York radio host Randy Credico in an effort to prevent Credico from contradicting Stone's testimony before the House Intelligence Committee.