Civil Libertarian Democrats Seek a Leader

Since they're at odds with their party's establishment

[W]ell more than half the House Democratic conference voted to defund a surveillance program overseen by a president of their own party. That's a pretty stunning fact that has gotten lost in the current debate.

So why hasn't this issue played out on the Democratic side like it has on the Republican side (i.e. in full view)?

Put plainly: It's a movement in search of a leader. There isn't one big nationally known player on the left that is pushing this issue in a way that Paul is on the right.