The Reform leader was speaking to Newsnight after an undercover report raised questions about party fundraising.
Related stories
How Trump's Education Department Changes Affect Campus Sexual Assault Cases
Daniel Jones Signing Deemed Big Offseason Mistake After Colts' Week 6 Loss
Packers HC Matt LaFleur Gives Update on Josh Jacobs' Status for Lions Matchup
U.N.C. Strikes Trump Deal to Keep Federal Funding
Trump Threatens California Election Officials With Jail. Could It Happen?
Map Shows Republican Chances of Losing Senate Two Weeks Before Midterms