Our Rebbeim, the Nesi’im [of Chabad] ordered that they [Chabad chassidim, in particular communal activists in Eretz Yisroel] distance themselves as much as possible from any form of support for a political party, regardless of which party, even the best one.I often hear it said: “A Lubavitcher chossid should not act in such and such a way because it will cause a chillul Hashem, and this will make those who observe or hear about this conduct less inclined to learn about Torah and Mitzvos in general and Chassidus in particular from chassidim.”
They also explained the reason behind this command in writing, and to a further degree orally: Our role is to be in the midst of the Jewish people in general in order to disseminate Jewish observance, and its inner dimension, to disseminate the teachings of Chassidus, in a way that one reaches even those who are still on the “outside.”
Thus, we are duty-bound to stay as far away as possible from anything that is liable to diminish the opportunity for this dissemination. This is so much so that if one harbors doubt, even a remote doubt [that one’s actions might detract from one’s ability to spread Chassidus], one should follow the strict path.
Igros Kodesh, Vol. 19, p. 251.
However, the above letter takes this a step further. The Rebbe is not saying that the Chabad movement should not openly affiliate with a political party because politicians are notoriously untrustworthy, or because most parties put forth platforms that contain principles somehow not consistent with Torah, or the like. Even if every politician in the party were scrupulously honest, and every part of the platform would be consistent with Torah and even with the teachings of Chassidus (unlikely as this may be), it would still be unacceptable for the Chabad movement to use its influence to promote this party, to in anyway participate in promoting the party, or even to publically endorse the party.
The reason for this is that some people who strongly identify with another party will then choose not to want to have anything to do with the Chabad movement and its teachings, because their affiliation with their own political group makes them unwilling to associate with those who support a rival group.
However, by maintaining a distance from such an affiliation, Lubavitchers can rightly say: “We are not only here to serve those who affiliate with a certain party—we are here to serve every single Jew.”
If we should be so careful in our public conduct that sometimes, in the interest of pursuing the goal of our movement, we should refrain from supporting otherwise worthy causes, all the more so should we be ever vigilant not to behave in any way inappropriately.