There's several different issues at play simultaneously. While net neutrality vs. not is obviously one of them, another is "who gets to make the rules", and both congress and the FCC are fighting over that power. Plus, there's the constant Republican vs. Democrat, and opposition party vs. President rhetoric involved as well. So - why do Democratic congress members vote against FCC net neutrality rules? Because they want to be writing the rules themselves. Why do Republican congress members invoke the spectre of big government? Because they also want to take power back from the FCC, and can attempt to score points against Obama with the same press conference.