Last year he was a member of a party group which called for her impeachment and expulsion from the party. Observers said his reversal of position appears intended to sound a clarion call for conservatives and Park's supporters who have taken to the streets in recent weeks to demand her reinstatement.

Kim, who led Gyeonggi Province from 2006-2014, has been mentioned as a potential presidential contender.

Even praising Park as one of the most "upright" politicians, Kim pointed out that her lack of communication with the press and her party rank-and-files led to the passage of the parliamentary impeachment motion.

Park was impeached by parliament on Dec. 9 over a corruption scandal involving her and her friend Choi Soon-sil. Both have denied all accusations.

The Constitutional Court has to determine whether to remove her from office or reinstate her by early June. (Yonhap)