Complex sentence: Ahn was criticised by the pro-DJ members of his party, calling the combination "1990 again," insinuating that Ahn wanted the People's Party to merge with the Bareun Party and Liberty Korea Party, much as three conservative parties combined in 1990.
Split into simpler sentences: Ahn was criticised by the pro-DJs of his party, calling the combination "Again 1990". This means that Ahn wanted People's Party to combine with Bareun Party and Liberty Korea Party, much as three conservative parties combined in 1990.