In a major setback Wednesday in London's High Court, two British judges rejected Assange's move to block extradition to face questioning in Sweden. Court officials said Wednesday that Assange plans to try to take the case to Britain's Supreme Court.
"He has indicated that he plans to launch an appeal," a spokeswoman for the Judicial Office said on condition of anonymity because she wasn't authorized to give her name. It is possible his request for an appeal will be turned down, making extradition virtually inevitable.
Wednesday's ruling is the latest reversal for Assange, whose secret-spilling organization is on the brink of financial ruin. The group has suspended publishing the sensitive government documents that drew the ire of governments worldwide because of money woes.
Assange has denied any wrongdoing in the alleged rape of one woman and the molestation of another in Stockholm last year. He and his followers have maintained the sex crimes investigation is politically motivated by those opposed to WikiLeaks.
He has deeply polarized public opinion, appearing on Europe's Most Wanted List while winning praise in some quarters as a brave advocate for freedom of speech and for challenging government power.
Assange did not seem angry or visibly upset outside London's High Court.
"We will be considering our next steps in the days ahead," he told reporters and supporters.
But experts said his legal options are now extremely limited.
"I think it's highly likely that he'll be in Sweden before the end of the year," said Julian Knowles, an extradition lawyer not involved in the case.
Vaughan Smith, the owner of the country mansion where Assange is living out on bail, said his friend's prospects appeared bleak. "It's not good news," he said.
Smith said Assange is concerned about the impact on his organization if he is sent to Sweden, fearing he would likely be held in prison as he contests the allegations against him.
"How can you run WikiLeaks from a jail? You can't," Smith said. "There is a pretty good reason for him not wanting to go to Sweden."
Assange has 14 days to decide whether to apply to the High Court, and then must try to persuade judges that there is a point of law to justify an appeal to Britain's Supreme Court.
The ruling means Assange will remain in Britain for at least several more weeks, and could potentially extend his fight against extradition into next year. Assange remains on bail, held under virtual house arrest at Smith's rambling country estate in southern England.
It's also not clear whether Assange has the money for a continued legal battle. In a recent dispute over his autobiography — a draft of which was published without his permission — the WikiLeaks founder revealed that he'd fallen out with his previous lawyers over the size of his bill and didn't have enough cash to sue his publishers.
Assange and his supporters say he's not drawing on WikiLeaks funds for his legal defence.
Claes Borgstrom, the lawyer representing the two Swedish women accusing Assange of sex crimes, told The Associated Press that his clients were both very pleased by the ruling.
"There's a sense of relief and it's a step in the right direction," he said.
He said the long wait for the ruling has been difficult for his clients, adding that more delays are likely.
"A lot points to that he intends to appeal once more," he said.
In the ruling, the appeal judges rejected key arguments from Assange's legal team. They said Sweden had the right to issue a warrant for Assange, rejected claims that the alleged offence had been inaccurately described, dismissed issues over Sweden's process for instigating criminal inquiries, and ruled that the prosecutors had been proportionate in their actions.
"This is self-evidently not a case relating to a trivial offence, but to serious sexual offences," the judges wrote, upholding an original court decision in February that Assange should be extradited.
Assange has said the sexual encounters were consensual, and his lawyer, Ben Emmerson, had previously argued the allegations would not be considered crimes in England.
The appeal judges said that apparent inconsistencies in some of the allegations against Assange should not affect his extradition to face questioning — even though those issues could be validly raised in any future trial.
With Assange one step closer to extradition, it's an open question whether his site can survive.
Only last week Assange warned that WikiLeaks was so low on cash it would have to stop publishing leaks and could shut down altogether in two months unless its funding improves.
Assange also faces possible legal action in the U.S., where prosecutors are weighing criminal charges.
Bradley Manning, the U.S. Army analyst suspected of disclosing secret intelligence to WikiLeaks, remains in custody at Fort Leavenworth prison in Kansas. His case is pending in a military court.
Some supporters in London carried placards outside the court Wednesday that said: "Free Assange! Free Manning!"
Raphael G. Satter and David Stringer in London, and Louise Nordstrom in Stockholm contributed to this report.