So...as of this announcement, there are 49 Republicans, 48 Democrats, and 3 independents in the US Senate. How does that give the democrats authority to set the agenda. (I don’t care about who “caucuses” with whom. You’re either a democrat, a Republican or independent.)
Well, "feelings" don't matter - who has the largest number of members in their caucus controls the chamber. And that at present is the Democrats.