The candidate who had topped Change UK's Scottish list for the European Parliament elections has withdrawn from the race after one day.
Joseph Russo was selected as the lead candidate for the new party in the Scottish constituency, should the UK take part in the elections in May.
However he has now announced on Twitter that he will not stand for election.
He said he was "not fully prepared" for the "personal scrutiny" he faced after "offensive" online posts came to light.
One of the new party's prospective London candidates, Ali Sadjady, also quit the race on Tuesday - hours after the party's lists were announced - over comments he had previously made on social media.
Change UK - which stems from the Independent Group of MPs who quit Labour and the Conservatives earlier this year - launched its campaign for the elections on Tuesday.
Mr Russo had topped the party's Scottish list, followed by David Macdonald, Kate Forman, Peter Griffiths, Heather Astbury and Catherine Edgeworth.
However, shortly after the list was announced, concerns were raised about old social media posts made by Mr Russo.
These have since been deleted, but screenshots appeared to show offensive comments about black women and Catholics, and that the police were targeting "low lying fruit" by arresting convicted sex offender Gary Glitter.
A spokesman for the party said that after discussion with Mr Russo about "several offensive Twitter posts", they had "agreed that he will stand down and is no longer on our list of candidates".