Sorry for the dumb question, but....

[Think. Again.]

...I'm confused.

In another thread, I came across this quote from republican person:

"“He (referring to trump) is endorsing Jim Jordan, and I believe Congress should listen to the leader of our party,” Nehls wrote on X, formerly known as Twitter."

Now, I know that when a person is the sitting President of the U.S., they are automatically the 'leader' of their respective party.

My question is:

Who is the leader of any given party when that party isn't in the whitehouse? And how is that person hired for that job?

Is trump being paid in a 'leader' position of the repub party like that guy nehls said? Because I thought some lady named Ro something was in that job(?).

Or is this nehls guy just making up sh!t? And if so, anyone know what the Ro person thinks about that?