Shinui party chairman Yosef "Tommy" Lapid and MK Avraham Poraz have cancelled the press conference due to take place Monday afternoon.
No immediate reason was given for the cancellation of the conference, at which it was anticipated that Lapid would announce his retirement from politics.
Shinui MKs disgruntled with the party list chosen Thursday held exploratory conversations with other parties about joining them ahead of the March elections.
Possibilities include Uzi Dayan's centrist Tafnit and Roman Bronfman's leftist Democratic Choice Party. There have been some contacts with Kadima members as well.
Though Lapid was reelected to the top party spot after a closer-than-expected election, Poraz was defeated by relatively unknown Tel Aviv councilman Ron Lowenthal.
Four MKs have joined Poraz in leaving the party, though the Poraz camp hopes that all 10 current Shinui MKs not chosen for the new list will take a united step.
"The most likely [option] is to form a new party with all these people that were backbone of Shinui," said MK Eti Livni, but she stressed that "all options are open."
She also pointed to the long-shot possibility of the new list being scrapped in favor of another round of elections, which could allow some ex-Shinui MKs to rejoin the party.
A member of Shinui's voting body who is part of Lowenthal's camp, however, dismissed the notion out of hand. "There's no talking about a new list. Why? Everything was done according to the book," he said, declaring that those who left "knew that they had no chance to be elected."
MK Reshef Cheyne, a Poraz supporter who had decided not to seek reelection before Thursday's vote, fired back that the issue was moot because those who made it to the list "are not going to give it up."
"I don't think anybody can fix this," Cheyne said. "I think that Shinui is finished."
But the Lowenthal backers questioned why Lapid would quit the party because of Poraz's loss.
"He might get used to the fact that the number two is not his best friend. You don't always have a couple at the head of the party," one said.