As a general rule, most out of power politicians and political parties, even extreme ones, are much better at pointing out the faults in the opposition, often accurately, than justifying their own agenda. But since their agenda isn't in place, it's much easier to dismiss criticism.
In the US, Republicans have good arguments against the Democrats, and vice versa. Neither one are as good at holding up their own end. Then there's the argument that they're both holding up ends of a very short rope, leaving lots of others out.
People in general often have the same behavior.