The race to choose a new Conservative leader – and therefore prime minister – will kick off tomorrow and a new PM will be in place on 5 September.

Rules for the leadership election were revealed on Monday evening, and mean MPs who put themselves forward to become leader of the Conservative Party will now need the backing of 20 other Tory MPs to get on to the ballot.

Candidates will then need at least 30 votes to proceed into the next round, chairman of the 1922 Committee Sir Graham Brady said. That would be just under 10% of Tory MPs so could narrow the field further.

He added that nominations will open and close on Tuesday, the first ballot will be on Wednesday and the second ballot on Thursday.

The new leader will be announced on 5 September after the summer recess, with Boris Johnson remaining as a caretaker prime minister until then.

If there are a large number of candidates after the nominations are in, Sir Graham said there could be hustings on Wednesday evening to help narrow down the field the following day.

He said there could be more ballots next week, probably on Monday, if the numbers are not whittled down fast enough.

So far, 11 MPs have publicly announced they want to replace the prime minister following his resignation last week.

According to Sky News’ tally, only Rishi Sunak and Penny Mordaunt have reached the 20 nominations threshold and only Mr Sunak has reached more than 30 to get through to the first round of voting.

However, many of the Conservative’s 358 MPs are yet to declare who they will be supporting.

Each time a leadership election takes place, the executive of the 1922 Committee of backbench Tory MPs determines the rules and procedures.

In 2019, an MP wishing to stand only needed the support of eight other Conservative MPs to get to the first round.

After the 1922 executive held its own election on Monday afternoon, with chairman Sir Graham re-elected, they voted on the new leadership race’s timetable and rules.

By increasing the number of MPs needed to nominate a possible candidate, the length of the whole process should be shorter.

In 2019 there were initially 10 candidates in the first ballot and six rounds of balloting were required before the final two candidates were known.

After the field is whittled down to two candidates they will face a ballot of party members based on one member one vote and the candidate who receives the most votes wins.