http://www.jewishpress.com/blogs/the-lid-jeffdunetz/worldwide-coven-of-witches-to-cast-spell-on-pres-trump-fri-night/2017/02/26/This is the time of year where we stress the mitzva of wiping out Amalek.
Shmot/Exodus 17:9 So Moses said to Joshua, Pick men for us, and go out and fight against Amalek. Tomorrow I will stand on top of the hill with the staff of God in my hand
Rashi
Pick men for us: Heb. אִנָשִׁים, mighty men, and God-fearing [men] so that their merit will help us (Mechilta d’Rabbi Shimon ben Yochai, Pirkei d’Rabbi Eliezer ch. 44, Yalkut Shimoni, Jonathan).
Another explanation: who know how to counteract witchcraft,
because the Amalekites were sorcerers.
When we hear about the mitzva to wipe out Amalek, current events helps us remember one of the reasons we don't like Amalek. Because they try to convince people that G-d does not supervise over the events of mankind in general and Jews in particular.
My working assumption is that these clowns that are casting their witch spells against Trump don't really have the power to affect anything, although they can convince people that they do.