The government is expected to announce some new names in senior roles - with widespread talk among senior sources that the prime minister will also set out a reorganisation of some government departments on Tuesday.
The weekly cabinet meeting has been pushed back an hour and will now begin at 10:30 GMT.
Rishi Sunak has been looking for a new party chairman for over a week now, following the sacking of Nadhim Zahawi.
One well-placed source told the BBC they expected Mr Zahawi's successor to be the Trade Minister Greg Hands.
Were that to be the case, that would mean Mr Sunak would be looking for a new trade minister.
We understand the current Business Secretary Grant Shapps - a former party chairman - will not be the new party chairman.
It is also thought the responsibilities of some government departments may be changed, with a reorganisation of what is currently the Department for Business, Energy and Industrial Strategy expected by some.
The prime minister promised last summer - when he was campaigning for the job - to re-establish a standalone Department for Energy.
Changing departments
The Westminster rumour mill had been alive with chat about a potential reshuffle all weekend, after requests were made for diaries to be shifted prompted suspicions from some.
Talk of a reshuffle had been dismissed by those around the prime minister. But when both The Sun and The Times reported expected changes, Downing Street refused to comment.
There was fury from some in Whitehall about what was seen as the prime minister's failure to tell his colleagues and the civil service before it was reported by journalists.
"There are a bunch of civil servants going to bed not knowing which department they're going to be working for in the morning," one source said.
"Surely they should have the courtesy of telling us first."
The Department of Culture, Media, Digital and Sport is also anticipating change. The current Culture Secretary Michelle Donelan is expected to take maternity leave this spring.
The Sun suggests the responsibilities of her department may be changed too - which would pose big questions for complex bits of legislation such as the Online Safety Bill.
When repeatedly asked to comment on or deny suggestions of a reshuffle or Whitehall reorganisation, a Number 10 source said "no comment".