It is believed that he would officially announce his resignation from the post after defending it over the last two weeks.
The announcement that the press conference would be held later today was sent to the media at about 11pm Tuesday, shortly after the Kedah Regency Council was believed to have adjourned.
It was learnt that the council had deliberated the issue of the mentri besar's position late into the night after meeting Opposition assemblymen on Tuesday afternoon.
The Star reported that Mukhriz had agreed to resign after a dramatic fortnight full of political twists and turns.
The pressure on Mukhriz reached a new level on Tuesday when he was asked for the third time in a week to sign the resignation letter.
Highly-placed sources indicated that Mukhriz was presented with the prepared resignation letter a little after 6pm.
The third attempt to have him sign the letter came after the three members of the Regency Council huddled in a closed-door discussion among themselves in the Regency Council office located at Wisma Darul Aman.
After that, the state secretary and the state legal adviser met with Mukhriz regarding the resignation letter.