Theresa May's Brexit withdrawal bill will not be published or debated until early June, the government says, BBC reports.
The prime minister is continuing to face pressure from her own MPs to resign following her pledge of a "new deal" on Brexit.
It comes after Commons leader Andrea Leadsom stepped down on Wednesday night over the PM's Brexit policy.
Downing Street has announced she will be replaced by Treasury minister Mel Stride.
Several cabinet ministers have told the BBC that Mrs May cannot stay in her post.
On Wednesday, Theresa May told the Commons that the legislation would be published on Friday.
Second reading is when MPs get a first chance to debate legislation, before deciding whether it should proceed to detailed scrutiny.