The reigning King of Spain, Charles III, was indeed a capable monarch, but his physical condition had become extremely dire. Joseph could not recall the exact year of his death, but it must be drawing near.
After that, it would be Antonio beside him who would ascend to the throne as the King of Spain—Charles IV.
Owing to the Bourbon bloodline shared by Spain and France, along with numerous colonial and economical conflicts with England in the Americas, France and Spain could be deemed natural allies.
Especially since Spain still possessed remnants of its former empire's splendor, not only did it have vast colonies and substantial revenues from gold and silver in the Americas, but it also maintained a fleet of considerable strength—about a third of the British Navy's power.