The defence team for WikiLeaks suspect Bradley Manning is planning to call 50 witnesses at next month's military hearing, promising to turn the proceedings into a detailed legal battle over the merits of the prosecution case against him.

The Bradley Manning support network, a group of sympathisers of the US soldier that has paid for the bulk of his legal fees so far, revealed that attorneys are preparing to launch a vigorous defence at the pre-trial hearing scheduled to take place at Ford Meade in Maryland on 16 December. Many legal angles will be pursued, with witnesses ranging from experts on whistle blowing to IT specialists who can comment on technical details relating to Manning's access to intelligence databases.

The strategy is unusual for such pre-trial hearings, known in the army as Article 32 proceedings. It is common at this stage for defence teams to limit their engagement to a minimum, in order to withhold from the prosecution elements of their approach that could be crucial in any eventual trial.

Manning's defence is being led by a civilian lawyer, David Coombs, who has avoided contact with the media ahead of the start of the military process. The support network, which has been in close contact with Coombs, says it it has contributed about $130,000 towards his legal fees.

Jeff Paterson, a founding member of the network, told a telephone press conference that Coombs would call as many of the 50 witnesses he has identified as the army will allow. If he is permitted to call all 50 – which is considered unlikely – the hearing will take much longer than the five days earmarked for it.

If he is not allowed to call many of the witnesses, Paterson said, Coombs will release the entire list of names for the public to see.

"Coombs intends to present a pretty vigorous defence on many different angles, which is how Bradley Manning himself envisioned being represented," Paterson said.

Manning was arrested in Iraq in May 2010 on suspicion that he was the source of the huge database of US embassy cables that was passed without permission to WikiLeaks. He has spent the past 18 months in confinement, much of it in the early stages in conditions that some say were tantamount to torture.

Ahead of the Article 32, the army has released details of the precise charges against Manning. The most serious count is "aiding the enemy" - a charge that technically carries the death penalty though prosecutors have indicated they will not press for that.

In addition, Manning is accused of 16 counts of wrongfully causing intelligence to be published on the internet knowing that it is accessible to the enemy; five counts of theft of public property or records, eight of transmitting defence information, two of fraud in connection with computers and five of violating army information security.

If convicted of all charges, Manning would face a maximum sentence of confinement for life.

His support network plans to hold a rally outside the Article 32 at Fort Meade on the morning of the hearing, followed by a march the following day – Manning's 24th birthday.

The five counts of theft of public records are being brought against Manning under the Espionage Act, the same law under which Daniel Ellsberg, the former military analyst who leaked the Pentagon Papers on Vietnam, was prosecuted in 1971. Ellsberg, an adviser to the support network, said that if Manning were found to be the source of the WikiLeaks documents, "he deserves our thanks and has my admiration. He is unreservedly a hero."

Ellsberg added that the WikiLeaks exposure of illegal war crimes by US forces in Iraq had been crucial to the decision of the Iraqi government to insist on legal jurisdiction over all American soldiers, which in turn forced the Obama administration to pull all remaining troops from the country.

"So there have already been major benefits from these disclosures," Ellsberg said.

Coombs has yet to indicate what legal arguments he will pursue in defence of Manning. Kevin Zeese, the main legal adviser to the Bradley Manning support network, said that one line of defence might be that Obama had rendered it impossible to stage a fair trial because he had improperly commented on the case.

In April Obama was engaged in a conversation at a fundraising event in which he appeared to suggest that Manning was guilty. The president said: "If I was to release stuff, information that I'm not authorised to release, I'm breaking the law. We're a nation of laws. We don't individually make our own decisions about how the laws operate."

Zeese said that Obama's comments amounted to "undue command influence". "President Obama is commander in chief, and the judge and all the jurors at Manning's trial will be under his command. That's a very serious problem."