He calls them the party of no -- correctly -- because the bulk of Republicans will stall or destroy anything and everything he supports, simply because he supports it. They'll even do it to things they proposed and supported in the past. They'll even do it if Obama wants to shrink government. They say no any time he says yes, simply because he said yes.
They have said publicly that their number one priority is to make Obama a one-term president. They don't care about anything else, and they have explicitly stated as much. So all they care about is trying to make him seem ineffective. They don't care about policy, or what's right for the country.