His testimony would mark a break from the low profile that Travolta and his wife, actress Kelly Preston, have kept since their 16-year-old son died from a seizure at a family vacation home on Grand Bahama island on Jan. 2.
Travolta, 55, skipped the publicity tour this summer for his latest film, "The Taking of Pelham 1 2 3." He posted a note on his personal Web site in June thanking his co-stars for their efforts to promote the picture, which gave the family additional time to grieve.
Prosecutors declined to say when Travolta might testify or whether he is in the country.
Former Sen. Pleasant Bridgewater and paramedic Tarino Lightbourne, who was among those who tried to revive Jett after he collapsed, have pleaded innocent to charges including conspiracy to commit extortion.
Before the start of jury selection, defense lawyers argued unsuccessfully for a delay, saying they needed more time to press prosecutors to hand over evidence.
A hearing is scheduled before another judge Wednesday on their request for materials that reportedly include recordings of the defendants' conversations with a lawyer for Travolta.
The pair allegedly threatened Travolta with a document that would have released emergency responders from liability if the family refused an ambulance. However, police said that did not happen in Jett's case. It is unclear why the pair allegedly believed Travolta would pay to keep the document from being released.
Both defendants have been free on bail.
Jett Travolta had a history of seizures and was found unconscious in a bathroom. A Bahamas undertaker said the death certificate listed seizure as the cause of death.