“Some US journalist came up to me and said: 'How can you say this about President Bush?' Well, I think what I said then was quite mild. I actually think that Bush is the greatest threat to life on this planet that we've most probably ever seen. The policies he is initiating will doom us to extinction.”
As quoted in "Livingstone says Bush is 'greatest threat to life on planet'" by Nigel Morris, in The Independent (18 November 2003), p. 5.
Help us to complete the source, original and additional information
Ken Livingstone 42
Mayor of London between 2000 and 2008 1945Related quotes

Comparing city council vote that stripped him of more powers to Saddam Hussein attacking Kuwait http://www.ctvnews.ca/canada/he-said-what-quotes-from-toronto-mayor-rob-ford-on-day-of-council-vote-1.1549474#ixzz2l7Nq3YQ9 (18 November 2013)
2010s, 2013

2000s, Bush's Lincolnian Challenge (2002)

Friday Sermon in Qom, Iran: US Wants To Bring the Ba'th Party Back Into Power http://www.memritv.org/clip_transcript/en/170.htm July 2004.
2004

“Well, I just want to say that George W. Bush is the syphilis president.”
As quoted in "Kurt Vonnegut's 'Stardust Memory'" http://www.freepress.org/columns/display/7/2006/1326, Harvey Wasserman, The Free Press (4 March 2006)
Various interviews

Latif Yahia, double for Uday Saddam Hussein, in I knew… Saddam (31 July 2007) Al Jazeera English
Attributed

In Following His Own Script, Webb May Test Senate's Limits, Washington Post, November 29, 2006, Michael D. Shear http://www.washingtonpost.com/wp-dyn/content/article/2006/11/28/AR2006112801582.html,

Remarks by the President at the Dedication of the National Museum of African American History and Culture at the National Mall in Washington, D.C. https://www.whitehouse.gov/the-press-office/2016/09/24/remarks-president-dedication-national-museum-african-american-history (24 September 2016)
2016