Last week, American Jewish activists were led to believe the April 13 trial would be rescheduled to just before or after Passover, which begins April 19.
The delay would have allowed the prisoners to dump their court-appointed lawyers and choose their own and would have given the new advocates more time to prepare their cases.
What happens next is anyone's guess.
"It's impossible to confirm anything, because for every person who tells you one thing, someone will tell you the exact opposite," said Malcolm Hoenlein, executive vice chairman of the Conference of Presidents of Major American Jewish Organizations.
Hoenlein has been spearheading American Jewish activism on behalf of the Jews, mostly through international diplomats and human rights groups.
The 13 Jews are mostly community or religious leaders from the southern cities of Shiraz and Isfahan. All are Orthodox and wear yarmulkes.
They were arrested in January and March 1999, along with eight Muslims. None has been formally charged, but all are accused of spying for Israel and the United States. Three of the Jews were released on bail in February, while the other 10 remain in prison.
Israel and the United States have vehemently denied the accusations.
Speaking out for the accused, Jews have recently demonstrated in the United States, France and Russia.
Prominent non-Jews are also speaking out now.
Egyptian President Hosni Mubarak told the European Jewish Congress on Monday that Iranian authorities had promised him they would "not implement capital punishment."
The same day, Palestinian leader Yasser Arafat said Tehran informed him that "the trial will be fair, and the prisoners will most probably be set free."
In the face of this mounting pressure, Iran is trying to airbrush its image as a brutal, undemocratic regime.
Iranian media reported that the chief of the Revolutionary Court, Judge Sadeq Nourani, took the unprecedented step last Friday of visiting the Jewish prisoners. Nourani reportedly wished them well and even presented each with a small, unidentified gift.
The media quoted two of the Jewish prisoners, both of them cantors, as expressing profound gratitude to Nourani.
"I could not believe that [Nourani] would come in person to my cell," Asher Zadmehr reportedly said. "Tears fell from my eyes, and I could not talk. I hope I will be pardoned and forgiven by the great leader."
The news report may be part of a good cop-bad cop strategy in an attempt to appease both the Iranian public and international community, said Pooya Dayanim, spokesman for the Los Angeles-based Council of Iranian American Jewish Organizations.
Dayanim noted that the report was followed a day later by a fiery public speech by senior Iranian cleric Ayatollah Ahmad Jannati. Jannati denounced the 13 as spies, and assailed all Jews as "by nature enemies of Muslims."
"People here often talk about the reformist and hard-line factions in Iran," said Dayanim. "But I believe they're just playing those roles. There is consensus in Iran on the Jewish question. They keep sending positive statements, but little positive action to back up those statements."
Iran seems deliberately ambiguous about the fate of the "Iran 13," said Hoenlein.
Compounding the problem, he added, is a Jewish leadership in Iran that is politically unsavvy.
"People hear what they want to hear, and they have their own perspectives," he said. "And the Iranian officials are purposefully engaging in a disinformation campaign to confuse and undermine the credibility of us and the people we're working with in Iran.''
From what Hoenlein has been able to distill, it seemed likely that the lawyers for the prisoners would enter court Thursday and be granted a request for an extension.
Then the trial, which Iranian judiciary officials have indicated would be a one-day affair, would actually be held April 18, the day before Passover begins, or at the end of the month, after the Jewish holiday.
Or, said Hoenlein, the Iranian judge may simply forge ahead with the entire trial.