He was first elected party leader in May 2007 . In May 2008 he became deputy leader for one year , before he became re-elected leader of the party in July 2009 , and once more in May 2010 . He was already party leader from May 2007 to May 2008 , and afterwards deputy leader for one year , before he became re-elected leader of the party in July 2009 , and once more in May 2010 .