Complex sentence: In 2004, he left the Conservatives to join the United Kingdom Independence Party (UKIP), and formed its South Sefton branch in 2005 to contest elections in North Merseyside.
Split into simpler sentences: In 2004, he left the Conservatives and joined the UK Independence Party (UKIP). He founded its South Sefton branch in 2005 in order to contest elections in north Merseyside.