Penny Mordaunt has thrown her hat in the ring to become the next prime minister after the dramatic resignation of Liz Truss.

The Commons leader said in a tweet: “I’ve been encouraged by support from colleagues who want a fresh start, a united party and leadership in the national interest.

“I’m running to be the leader of the Conservative Party and your prime minister – to unite our country, deliver our pledges and win the next general election.”

Ms Mordaunt came third in the previous leadership race won by Ms Truss in September. Rishi Sunak, the former chancellor, came second.

Ms Mordaunt needs to secure the backing of at least 100 Tory MPs by Monday afternoon to stay in the race.

Nominations opened on Thursday and will close at 2pm on Monday – with a leader to be chosen by the end of the week.

In the last leadership election, Ms Mordaunt won 105 nominations, behind Mr Sunak’s 137 and Ms Truss’s 113.

Ms Truss won the final round of voting among Tory party members after campaigning on a mandate to cut taxes to boost economic growth.

This ultimately proved to be her downfall after her mini-budget unleashed turmoil in the financial markets, forcing her to sack Kwasi Kwarteng as chancellor and make a series of U-turns on the economic policies that brought her into office.

Ms Truss resigned 44 days into her premiership, making her the shortest-serving prime minister in modern British history.