Chair choosing to participate in the debate by making one of the members a chair.

[Guest Lina]

What would be a valid reason for the chair to give the responsibilities of the chair to a member in order to be able to debate and vote on a motion?

[George Mervosh]

22 minutes ago, Guest Lina said:

What would be a valid reason for the chair to give the responsibilities of the chair to a member in order to be able to debate and vote on a motion?

He need not state a reason, nor does RONR provide a list of reasons.  See FAQ#1 as well.  https://www.robertsrules.com/faq.html#1

[Sophie]

Okay so in a situation where the assembly is debating on a motion that is extremely important to the organization and all the members have overlooked an important piece of information on the motion, what does the chair say to relinquish the  responsibility's of the chair so that he can speak and vote on the motion. And what does the new chair say after the motion is either adopted/lost and wants to give the responsibility back to the original chair?

[Richard Brown]

Agreeing with Mr. Mervosh, if the chair intends to enter into debate, he should temporarily relinquish the chair to the vice president or to some other person if a vice president is not available.  This is what RONR says about the subject on page 395:

To participate in debate, he must relinquish the chair; and in such a case he should turn the chair over:
    a)    to the highest-ranking vice-president present who has not spoken on the question and does not decline on the grounds of wishing to speak on it; or
    b)    if no such vice-president is in the room, to some other member qualified as in (a), whom the chair designates (and who is assumed to receive the assembly's approval by unanimous consent unless member(s) then nominate other person(s), in which case the presiding officer's choice is also treated as a nominee and the matter is decided by vote).

[Rob Elsman]

There is nothing in particular that needs to be said. The presiding officer might even just use a hand signal or say the vice president's name.

[Gary Novosielski]

Do you have a Vice President?