The negotiations leading to the first elections of modern Poland after the fall of the USSR brought Tadeusz Mazowiecki to power. Solidarność finally won the battle it had been waging for so long. Yet the first centrist tendencies quickly began to emerge within the movement. The Kaczyński brothers gradually asserted their hostility towards the great figures of the former democratic opposition, such as Tadeusz Mazowiecki, Bronisław Geremek, or Jacek Kuroń. They chose to side with Lech Wałęsa, who felt isolated in Gdańsk and betrayed by his former friends, and created their own party, the "Centre Agreement", in 1990. The latter advocated for accelerated post-Communist evolutions and wished to remove from the political process the political representatives inherited from the previous regime. The two brothers won their bet: Lech Wałęsa was elected President in November 1990, and the Kaczyński brothers, who were then 41 years old, became President Wałęsa’s closest collaborators. Lech was in charge of security matters, while Jarosław became Head of the President's Chancellery.
The idyll between the Kaczyński and Wałęsa was short-lived. From 1991, their opinions regarding the attitude to be adopted towards political executives who participated in the Polish communist regime began to differ. More fundamentally, Lech Wałęsa became less and less tolerant of the two brothers’ growing independence, as they started to pursue their own political agenda. Jarosław and his brother were dismissed from the presidency, and switched to the opposition.
The "Centre Agreement" became an opposition party, which lost momentum and was marginalized throughout the 1990s. The only message the two brothers carried at the time focused on the defense of peripheral Poland (the countryside and small towns) against the liberal urban elites. Lech and Jarosław also held an increasingly radical discourse regarding the memory of the communist period. Indeed, in the context of the debate on the Lustration Law, they demanded that former security informants be treated with intransigence. This strategy aimed to give the Poles a moral compensation for the material difficulties the country was facing in the 1990s - years that were marked by the radical liberalization of the economy.
It was not until 1997, and Jerzy Buzek’s government, that the Kaczyński brothers returned to power. The Prime Minister appointed Lech as Minister of Justice. This strategic function increased the latter’s popularity, thanks in particular to his highly publicized fight against corruption. Meanwhile, Jarosław regained a parliamentary seat in the legislative elections that same year.