Complex sentence: Chief Minister Katy Gallagher resigned from the Assembly on 23 December 2014 to pursue a seat in the Australian Senate, ahead of Gallagher's resignation, media predicated that Fitzharris would be the most likely candidate to take Gallagher's Assembly seat.
Split into simpler sentences: Chief Minister Katy Gallagher resigned from the Assembly on 23 December 2014 to pursue a seat in the Australian Senate. Ahead of Gallagher's resignation, media speculation was that Fitzharris would be the most likely candidate to take Gallagher's Assembly seat.