text: MEP Nathan Gill said he "could not stay in a party that suddenly represented all the things that for 12 years I said it didn't represent".
  Ms Waters, who founded the Sharia Watch pressure group, is one of 11 candidates in the race.
  Her bid has split the party, with many angry she has been allowed to run.
  Former Labour activist Ms Waters believes her anti-Islam message, including a proposed ban on burkas, the closure of sharia councils and a temporary freeze on all immigration, will appeal to many voters.
  She has argued UKIP could regain support if it had the "guts" to be "honest about Islam" and challenge the view that it had "nothing to do" with jihadist violence.
  But Mr Gill said he could not support those views and said "a lot of my colleagues feel the same way as well".
  He told BBC Radio Wales' Sunday Supplement programme: "I don't have a dog in this race, I am not backing any of the candidates.
  "But I do know that I have got red lines and if I see the party going in any direction that it absolutely should not be going in then I cannot remain a member of that party."
  The candidates to replace Paul Nuttall - who stood down after UKIP's poor performance in June's general election - are:
  Voting papers will be sent to party members over the next few weeks and the new leader will be announced at the party's annual conference in Torquay, held on 29 and 30 September.
  Mr Gill also criticised the party's delay in addressing concerns raised about UKIP assembly member Michelle Brown, following a row over racial slurs she made about a Labour MP.
  The North Wales AM called Streatham MP Chuka Umunna a "coconut" in a recorded call in May 2016 to her then senior adviser Nigel Williams. She later apologised.
  Mr Gill claimed the issue, which the party postponed making a decision on at its National Executive Meeting, had been "kicked into the long grass".
  "I have said very clearly that I think that Michelle Brown should be expelled from the party," he said.
  "We have to show, very clearly, what we are not - and we are not a racist party and I fought so strongly for that."
target: The former leader of UKIP in Wales has said he would leave the party if anti-Islam campaigner Anne Marie Waters won the leadership election.