Since he promised to do so, I presume he will come.

Think : have a particular belief or idea.
Guess : estimate or conclude (something) without sufficient information to be sure of being correct.
Suppose : think or assume that something is true or probable but lack proof or certain knowledge.
Believe : accept that (something) is true, especially without proof.
Presume : suppose that something is the case on the basis of probability.

Synonym of Presume is Suppose