Pakatan Harapan and PAS' inability to reconcile on a common candidate for the opposition in the Kuala Kangsar and Sungai Besar by-elections may see Umno retaining both seats in three-corner fights.

However, political analyst Wong Chin Huat said the key determinant in both by-elections will be the ability of former premier Dr Mahathir Mohmad and his rebels to hurt Umno.