Netanyahu said he would apply "Israeli sovereignty over the Jordan Valley and northern Dead Sea", the BBC reported on Tuesday.
Such a move would be popular with right-wing parties which he would have to depend upon to form a coalition but fiercely opposed by Palestin.
Israel has occupied the West Bank since 1967 but stopped short of annexation.
Netanyahu, who leads the right-wing Likud party, is campaigning ahead of general elections next Tuesday.
Polls suggest Likud is neck-and-neck with the opposition centrist Blue and White party and may struggle to form a governing coalition.
Palestin claim the whole of the West Bank for a future independent state. Mr Netanyahu has previously insisted that Israel would always retain a presence in the Jordan Valley for security purposes.
Israel occupied the West Bank, along with East Jerusalem, Gaza and the Syrian Golan Heights, in the 1967 Middle East war.
It effectively annexed East Jerusalem in 1980, and the Golan Heights in 1981, although neither move was accepted internationally for decades.
The Donald Trump administration has since recognised both steps, overturning previous US policy.
The fate of the West Bank goes to the heart of the Israel-Palestinian conflict. Israel has built about 140 settlements there and in East Jerusalem which are considered illegal under international law, though Israel disputes this.
More than 600,000 Jews live in the settlements, which the Palestin want removed.
( With inputs from IANS )