At that time the people of Israel were divided: Half of the people supported Tibni son of Ginath as king, and half supported Omri.
Solomon observes (Pro 28:2) that for the transgression of a land many were the princes thereof (so it was here in Israel), but by a man of understanding the state thereof shall be prolonged - so it was with Judah at the same time under Asa. When men forsake God they are out of the way of rest and establishment.
Commenting on 1 Kings 16:15-28
For he walked in the way of Jeroboam the son of Nebat, in his sin wherewith he made Israel to sin,.... Worshipping the calves; to provoke the Lord God of Israel to anger with their vanities; these, and whatsoever idols else were worshipped by him, see Kg1 16:13.
Then were the people of Israel divided into two parts--The factions that ensued occasioned a four years' duration (compare Kg1 16:15 with Kg1 16:23), of anarchy or civil war. Whatever might be the public opinion of Omri's merits a large body of the people disapproved of the mode of his election, and declared for Tibni.