The dissolution of the Communist Polish United Workers' Party (PZPR) in 1990 marked the end of an era. Poland's opposition Solidarity movement had swept the partially free elections of 1989 and formed a government under Christian-democratic intellectual Tadeusz Mazowiecki, who democratised the country and, under the finance minister, the economist Leszek Balcerowicz, pursued radical economic reforms to turn the country's planned economy into a market economy. This led to much criticism of the government, but with Mazowiecki's popularity sky-high and Solidarity forgetting its role as a trade union in its unquestioning support of the government, this criticism initially remained beneath the government's notice. Mazowiecki was also criticised for not moving away from communism quickly enough for some Solidarity supporters' liking. These supporters accused him of failing to purge ex-communists from the administration and from state-owned enterprises, and of allowing them to maintain power over the market by taking over privatised companies. Lech Walesa of all people took it upon himself to become the leading critic of the government, surprising Mazowiecki by what he saw as demagogy on Walesa's part.
As the conflict between Mazowiecki and Walesa, known as the 'war at the top', deepened, Mazowiecki began to see Walesa as a danger to Poland's fledgling democracy. The two stood against each other in the first free presidential election in 1990, which Walesa won in a landslide, while Mazowiecki failed even to make it to the run-off, coming third behind the populist Polish-Canadian businessman Stanislaw Tyminski, who denounced the new Solidarity establishment and Mazowiecki's economic reforms. Solidarity itself splintered as a result of this election, with liberals who supported Mazowiecki, including Jacek Kuron, Bronislaw Geremek, and Adam Michnik, creating the Democratic Union, and conservatives who supported Walesa creating the Centre Alliance, lead by brothers Jaroslaw and Lech Kaczynski. Another liberal faction, led by Donald Tusk, formed the Liberal Democratic Congress, the Christian-nationalist faction of Solidarity formed the Christian National Union, and the branch of Solidarity that organised farmers split off to form the Peasants' Agreement. Solidarity's few social democrats formed their own parties too, Labour Solidarity and the Democratic-Social Movement. Attempts by the two to form an alliance including the radical Polish Socialist Party came to nothing. Tyminski himself tried to get in on the action by creating his own party, Party X. A rump Solidarity, by now reduced to nothing but its trade-unionist wing, continued under the leadership of Marian Krzaklewski.
Meanwhile, on the post-communist side of politics, the PZPR had transformed itself into the Social Democratic Party of the Republic of Poland, which contested elections as part of the Democratic Left Alliance coalition, and the United People's Party, the agrarian former satellite party of PZPR became simply the Polish People's Party, to remind voters of the opposition party of the same name that existed in the late 40s.
One can therefore imagine that Poland's first free parliamentary elections in 1991 did not exactly get off to an auspicious start. The Sejm had started work on a new electoral law to replace the first-past-the-post system used in the communist era as early as mid-1990, but Walesa deliberately delayed passage of the law to strengthen his own political position vis-a-vis the parliament which, unlike, Walesa himself, had not been elected in a truly free election and was increasingly open to accusations of illegitimacy. A back-and-forth between the President and the Sejm ensued, with Walesa vetoing the Sejm's proposed law and submitting his own amendments, which the Sejm in turn rejected. In the end, the Sejm was able to override Walesa's veto and push through its own version of the electoral law, which, being intended to favour the myriad micro-parties which had split off from the anti-communist Solidarity movement, ended up being a radical form of proportional representation with no threshold to exclude smaller parties and avoid fragmentation.
The result was a predictable mess, as over a hundred different parties ran in the election, deeply confusing most people and probably contributing to the low turnout of just 43.2% of eligible voters. The eventual 'winner', the Democratic Union, received just a little over 12% of the vote and 60 seats out of 460, just barely ahead of the Democratic Left Alliance. Observers, both in Poland and abroad, were shocked by the success of radicals, as the Christian National Union (running under the nom-de-guerre Catholic Election Action, and almost openly backed by the influential Catholic Church), Janusz Korwin-Mikke's radical libertarian Real Politics Union, the Polish Socialist Party (benefitting from its association with the historical party of the same name and its strong campaign against privatisation and ex-communist influence in government and business), and the anti-semitic National Party won much more support than the incredibly flawed opinion polls had predicted. Other parties profited from peculiarities of the electoral law to win more seats than the number of votes they had received would suggest, notably the ultra-nationalist Confederation for an Independent Poland which created multiple front parties to run in the election alongside the main party, which probably netted them more seats than they would have otherwise received and the Real Politics Union which formed an exotic alliance with the centrist Democratic Party which, according to post-election estimates, gained them an additional dozen or so seats as opposed to one or two for the Democrats. The only consolation was that Tyminski's Party X did not get very far, due to a scandal just before the election in which its campaigners were caught forging signatures for the party's lists leading to most of the party's candidates being disqualified. In the best possible summary of the Polish people's dissatisfaction with politics, the satirical Polish Beer-Lovers' Party, founded by comedian Janusz Rewinski, actually won 16 seats in the Sejm.
With a horribly fragmented Sejm dominated by the right and far-right, forming a government would inevitably prove to be a nightmare.