Nadine Dorries refuses to resign officially until No 10 explains her lack of peerage | Nadine Dorries

Nadine Dorries has said she will not formally resign until after she gets answers from ministers about why she did not get her peerage, after Downing Street earlier heaped pressure on her to stand down as soon as possible.

The former culture secretary said last Friday she would “immediately” step down, after she was denied a peerage in Boris Johnson’s resignation honours.

The Conservative party has moved the motion, known as a writ, for byelections in Johnson’s Uxbridge and South Ruislip constituency and Nigel Adams’s Selby and Ainsty seat as they formally resigned with a letter to the chancellor on Tuesday. But Dorries is yet to formally tender her resignation to Jeremy Hunt, frustrating Rishi Sunak’s attempts to prepare to replace her.

In a series of tweets on Wednesday night, Dorries said: “There is much speculation about the time at which I become appointed the bailiff of Northstead Manor, as part of the arcane resignation process when standing down as an MP.

“To put an end to this … I am awaiting responses to my subject access requests submitted to HOLAC [the House of Lords appointment committee], cabinet secretary and the Cabinet Office, where I will then take the time to properly consider the information I am provided.

“I have requested copies of WhatsApps, text messages, all emails and minutes of meetings both formal and informal with names of senior figures unredacted. My office continues to function as normal and will of course continue to serve my constituents of Mid Bedfordshire as we have done for the last 18 yrs until this time.

“It is absolutely my intention to resign, but given what I know to be true and the number of varying and conflicting statements issued by No 10 since the weekend, this process is now sadly necessary.”

Earlier on Wednesday, the prime minister’s press secretary said Sunak was “always disappointed” to see MPs leaving the house, but noted that it was “unusual” that Dorries had not yet formally resigned. “We are moving on with the two byelections of Uxbridge and Selby,” she said. “It’s obviously unusual to have an MP say they will resign with immediate effect and for that not to take place.

“The prime minister believes the people of Mid Bedfordshire deserve proper representation in this house and he looks forward to campaigning for the Conservative candidate in the byelection.”

Dorries, a fierce Johnson ally, is inflicting more pain on the Tory party by delaying her official resignation. With the delay, Sunak could face an autumn byelection that would ruin his chances of trying to reset the party around its conference.

A senior Conservative MP has accepted that the Tories are expected to lose all three byelections. If Dorries hands in her resignation soon, all three byelections could be held on one day, floated as 20 July. “It will be a complete washout. Once again, Rishi Sunak’s attempts to reset the party are hampered by another Boris drama. The prime minister must think big picture now.”

The delay has left Dorries’s constituents in Mid Bedfordshire in limbo. A number of Conservative voters have criticised her record, describing her as an “absent MP who is too focused on writing books”.

The Conservative party chair, Greg Hands, paid a visit to Dorries’s constituency on Sunday after at least 130 Liberal Democrat activists descended on the area in an attempt to win over voters.

The byelections have been triggered by “political tantrums” over peerages, according to the Labour leader, Keir Starmer, who has said Johnson and Sunak are damaging the UK’s reputation internationally.

Dorries, who accused Sunak of “duplicitously and cruelly” blocking her elevation to the House of Lords, had said she would be standing down with immediate effect.

CCHQ had been holding byelection drills for at least a month, the Guardian understands, before Dorries, Johnson and Adams announced their intentions to quit in order to accept peerages, amid claims Johnson was told as early as March that a peerage for Dorries would be rejected.

The drills consisted of outlining what the priority issues within each seat were, and which ministers should make visits to each constituency and why.