Verb for describing the act of someone who seemingly speak confidently on a subject he/she does not know well

I am looking for a verb (or phrasal verbs) for describing the act of someone who seemingly speaks confidently on a topic he/she isn't actually sure of (he/she knows it inside). It is not like "bullshitting" because that person sounds like he/she actually knows stuff and is able to fool people (but in reality is just making bold claims, promises, spilling unsubstantiated facts walking in circle in retrospect). It is usually coming out of someone who is an "elite" in society, or is trained/experienced in public speaking.

Solution 1:

To do this is to ultracrepidate ("to criticize beyond the sphere of one's knowledge" -- Chambers). But I wouldn't like speculate on how likely it is that your listeners know that word.