Original: He was Governor of Bayelsa State from 9 December 2005 to 28 May 2007, and was sworn in as Vice President of the Federal Republic of Nigeria on 29 May 2007.
Simplified: He was Governor of Bayelsa State from 9 December 2005 to 28 May 2007, and became the in as Vice President of Nigeria on 29 May 2007.