In 1792 a number of Polish diplomatic missions were cancelled, and Ankwicz was recalled to Warsaw. This meant that he lost his main source of income. He was able to briefly return to Denmark, but the end of the Polish–Russian War of 1792 (after the passage of the Constitution of 3 May) saw him in Warsaw once again. Known for his lavish lifestyle, poor investments and as a gambler, he quickly fell in debts and was recruited by Russian ambassador and Jacob Sievers. He became associated with the Targowica Confederation. Subsequently, he was known for his support of foreign powers (Austro-Hungary, Prussia, Russian Empire), most infamously during the last Sejm of the Commonwealth - the Grodno Sejm of 1793, he was the leader of the "Russian Party" and the deputy who concluded that the unwillingness of other deputies to speak (threatened by Russian soldiers present in the room) means that they accept the demands of the Prussian and Russian Empires (the Second Partition of Poland). For that he was rewarded by his Russian masters with a pension and a position in the Permanent Council.