Senior Lib Dems are understood to be preparing to unveil their latest recruit at the party’s autumn conference in Bournemouth next month.
A party source said today: “There are conversations going on with lots of different people.”
Dr Wollaston was elected as a Conservative MP in 2010. She was one of three Tories who quit in February to join what would become Change UK, but left that party in June.
She said today she had joined the Lib-Dems to try to stop a no-deal Brexit, telling the BBC Radio 4 Today programme: “The more people that join the Liberal Democrats and make that unequivocal case the better.
“The most significant feedback I got over the European election was that people wanted to see a single unified force making the case against no deal.”
Ex-Labour MP Chuka Umunna, who also helped to set up Change UK, joined the Lib Dems in June. The party now has 14 MPs.