An interesting observation from Lord Acton:
At all times sincere friends of freedom have been rare, and its triumphs have been due to minorities, that have prevailed by associating themselves with auxiliaries whose objects often differed from their own; and this association, which is always dangerous, has been sometimes disastrous, by giving opponents just grounds of opposition, and by kindling dispute over the spoils in the hour of success.
This passage by itself doesnt argue for or against any particular alliance. It makes the point that alliances are advisable (as they must be if it is indeed true that defenders of liberty have never succeeded except by allying with defenders of something else) but also that they are extremely risky and sometimes extremely harmful. All facts worth keeping in mind though by themselves they dont offer any concrete guidance.