Complex sentence: Jones stood down at the 2001 election in order to spend more time in the Assembly, when in the summer, he as elected President of Plaid Cymru with 77% of the vote over Helen Mary Jones.
Split into simpler sentences: Jones stood down at the 2001 election to spend more time in the Assembly. In the summer, he was elected President of Plaid Cymru with 77% of the vote over Helen Mary Jones.