Simplify the following text for a Grade 10 native English-speaking person.
Original: On 18 January 2007 , he announced his decision to step down from the posts of minister-president and party chairman by 30 September , after having been under fire in his own party for weeks .
Simplified: On 18 January 2007 , he said he no longer wanted to be minister-president and party leader by 30 September , after having been criticize by his own party for weeks .