It is always sensible to prepare for disaster, whether natural or man made.
An EMP attack is not IMHO that likely, but it COULD happen and most of the preps would be useful for other disasters also, so prudent to prepare.
I doubt that the colour of the party in charge at the time would much influence either the risk of such an attack occurring, nor the severity of the consequences.

It does however speak volumes that politicians are even speaking about such subjects, rather than the traditional "vote for me and everything will be just fine"

Likewise, one should not IMHO speculate overmuch on from where such an attack might come, concentrating instead on mitigating the consequences if it does come.

I recommend the novel "one second after" for a fictional but in my view believable account of an attack and the grave consequences thereof.