For a weaker belief:
* Suspect: This implies you have some doubt but think it's likely.
* Assume: You are taking something for granted without certainty.
* Conjecture: You are forming an opinion based on incomplete information.
* Surmise: You are making a guess based on evidence or reasoning.
* Presume: You are taking something as true without proof.
For a slight difference in belief:
* Almost believe: This is a straightforward way of saying it.
* Mostly believe: This emphasizes the majority of your belief.
* Tend to believe: This suggests a leaning towards believing, but not full conviction.
* Be inclined to believe: Similar to "tend to believe."
For a different nuance:
* Accept: This implies you are willing to acknowledge something as true, even if you don't fully believe it.
* Acknowledge: This is similar to "accept," but it focuses on recognizing something exists, not necessarily believing it.
The best word for you depends on the specific situation and the type of "almost believe" you want to express.