Porritt ran to become the Liberal Democrat candidate for the parliamentary constituency of Sutton and Cheam for the 2024 general election.

[16] She later explained as part of a speech to her party's annual conference that one of the reasons she had been forced to leave Camden was due to the areas high house prices.

[13] The Liberal Democrats won 27% of the vote, winning three seats, so Porritt was elected as a Member of the European Parliament.

[20] Porritt was reported to be "seriously considering" putting her name forward to be the Liberal Democrat candidate in the 2021 London mayoral election after Siobhan Benita withdrew from the race following its postponement from the original May 2020 date.

[21] She won the selection against the option to reopen nominations on 13 October 2020 after the only other shortlisted candidate, Geeta Sidhu-Robb, was suspended from the Liberal Democrats following antisemitism.