Catherine was supported by the Prussian monarch, Frederick the Great, who hoped to eventually annex Polish provinces of Royal Prussia and Greater Poland.

They were not aware of the fact that the Russians and their Prussian allies had previously signed a secret pact, which stipulated the use of a military force to support Poniatowski.

As early as October 17, 1763, Catherine wrote a letter to Frederick, in which she expressed the opinion that from all candidates to the Polish crown, Poniatowski was the least popular one, therefore, he would be most grateful to those who had made him monarch.

The Potockis, who called themselves the Republicans, on the other hand, supported the notion of Golden Liberty, together with liberum veto.The first clash between the two camps took place during the Convocation Sejm, which began on May 7, 1764.

The ceremony took place at St. John's Archcathedral, Warsaw, and the new king, to dismay of conservatives, did not put on traditional Polish clothes, preferring to wear instead a 16th-century Spanish outfit.

Poniatowski’s election was not at first recognized by several European states, such as France, Austria and the Ottoman Empire, which saw the new monarch as Catherine’s tool.