The Change UK leader said she would not allow Tony Blair to join her party, claiming he was too "tarnished".
The MP for Ilford South called for a "fundamental reform" of Britain's political system.
The MP asked people to "bear with" the new party, after two of its candidates were dropped over offensive tweets.
Rachel Johnson, the sister of Conservative MP Boris Johnson, has been revealed as MEP candidate for Change UK ahead of the European elections in May.
Campaign group Change.org UK is seeking legal advice over the rebranding of The Independent Group as 'Change UK'.
The Conservative leadership did "nothing at all" to reach out to Heidi Allen before she resigned this morning, the MP has revealed.