The BBC reports that difficulties in talks between the Tories and the Democratic Unionist Party (DUP), who they paired with to form a majority government, mean that they didn't get around the writing the speech until much later than usual.
It hit headlines after Government sources revealed the speech - used to outline the PM's agenda for the year - would be pushed back amid Tory turmoil following the shock General Election hung Parliament.
He said talks would start next week, but not necessarily on Monday.
THRONE OUT When is the Queen's Speech, why is it delayed and what happens at The State Opening of Parliament?
Foreign Secretary Boris Johnson, who has rejected suggestions he is plotting a leadership bid, described Mrs May's speech to the '22 as a "stonking performance", adding on Twitter: "One team going forward together for the UK".
A Labour spokesman said: "Number 10's failure to confirm the date of the Queen's Speech shows that this government is in chaos, as it struggles to agree a backroom deal with a party with abhorrent views on LGBT and women's rights".
Mrs May also told anxious Tory MPs she will review a planned shake-up of school funding after complaints that voters raised the issue repeatedly during the campaign.
Also in doubt is the first meeting between David Davis, the Brexit secretary, and Michel Barnier that was also due to take place on Monday.
Another Tory MP said there was no discussion at the meeting of how long Mrs May would remain in post, adding: "she's won, she's got to be PM". "This isn't just going to be a Tory Brexit, this is going to have to involve the whole country".
It is read by the Queen from the Throne in the House of Lords at the State Opening of Parliament.
Additional delay could be caused because the Queen's Speech is written on goatskin parchment paper, which requires several days for the ink to dry.
With her authority diminished after failing to secure a majority in the election last week, Mrs May faces the prospect of relying on the DUP to make sure the Queen's Speech passes.
"This is an utter humiliation for Theresa May, it is time to stop trying to cling to power and time to admit enough is enough", Mr Farron said.
Theresa May is set to meet DUP leader Arlene Foster tomorrow in order to finalise the terms of an agreement between their respective parties.