Since Reid is a member of the legislative branch as are house members might not he be acting against the interest of the Senate?
Yes, he is, but these are interesting times.
Obama, in casual remarks a few weeks ago, referred to the Democrats as "the governing party". An interesting turn of phrase, for sure, for any of the few Americans who remember the Warsaw Pact nations' political systems.
As recently as 1967, when the Democrats in the Senate tried to exercise the "nuclear option" to end the filibuster (with 64-36 majority and VP Hubert Humphrey in the chair!), the chair was overruled 46-54, because a majority of Senators of both parties understood that the Senate had institutional interests that transcended party. This is no longer the case.
The Democrats are united (with the possible exception of Manchin) around the looming coup d'etat which will end the Republic forever, because they "just want to be on the side that's winning". They would rather be members of the governing party than Senators, IOW.
And the Senate Republicans have, for the most part, smelled the coffee, the same coffee that Rep.Peter King is drinking.
The GDR had opposition parties. The parties had leaders, but no members. Their leaders had cars, and state salaries, and seats in the Volkskammer, and as long as they recognized the Leading Role of the KPD they were good to go.
The Republicans and the Democrats are no longer playing the same game. The Republicans in the House think the Old Rules are still in effect. The Democrats know they are not.
Interesting times we live in.