Morawiecki spoke after PiS leader Jarosław Kaczyński announced earlier in the day that "30-odd" lawmakers had resigned from the party after refusing to sign declarations stating they did not belong to outside political associations.
The requirement primarily targeted members of Morawiecki's Development Plus group.
Morawiecki told reporters that none of the lawmakers aligned with him had complied with the ultimatum issued by the party leadership.
He said he had made new proposals earlier on Friday in a last attempt to avoid a split.
Under the party's rules, refusing to sign the declaration was treated as a resignation.
PiS leaders are expected to formally acknowledge the departures at a meeting on Tuesday.
Speaking at a press conference, Kaczyński said: "That's simply how things turned out," and took no questions.
'Dear colleagues, you schemers'
At his own news conference, Morawiecki put his camp's size at 40 MPs, a senator and three MEPs, and said they had "fought for the unity of the PiS camp until the very last moment."
The former prime minister called the ultimatum an "intrigue," arguing that he and his allies "could not accept being forced to sign a loyalty pledge that would in effect have stopped us operating in the format we agreed two or three months ago."
"That alone was a poor idea, dear colleagues, you schemers," Morawiecki added, declining to name those he meant.
He gave no direct answer on whether a new party would be formed.
"We are surprised, we need to discuss our plans," he told reporters, saying that he still saw room for reconciliation before Tuesday's meeting, to which he said he had not been invited.
Political scientist Agnieszka Zaremba told Polish state news agency PAP that she was surprised by the scale of the split, saying it showed Morawiecki's base within PiS was stronger than previously thought.
She linked the crisis to organisational problems within the party since it lost power in 2023, as well as a regional leadership reshuffle two years ago that she said had left some activists feeling marginalised.
"PiS is Jarosław Kaczyński's child," Zaremba said. "I wonder whether succession is even possible in this party."
(ał/gs)
Source: PAP