"Overthrow" is a strong word for talking about the dissolution of a famously inept and lost minority government...
It's also worth pointing out that the government in question only had what - 133 votes or so? It wasn't as if it was a strong government that was forced out of power - it was a weak government that simply couldn't survive.
Wałęsa huddled with his Soldiarirty mates, ex-PZPR types, right-wing Catholics, Polish nationalists, Jewish agnostics from KOR and peasant activists and conspired in a backroom to overthrow the government.
Sounds like to me that a broad selection of Polish society was against a weak and unpopular minority government.
The situation was frankly ridiculous then. The two biggest parties (Mazowiecki's Freedom Union and Kwasniewski's SLD) were openly against the government, the Sejm was forcing Olszewski to stay as Prime Minister against his will - all in all, it was a deeply unpopular and weak government.
There's a good article here that sums it all up nicely - countrystudies.us/poland/68.htm
The outgoing government launched unprecedented personal attacks on Walesa, accusing him of presiding over the recommunization of Poland.
Just found this cracking little statement.
Although Olszewski was a PC member, with his Premiership and fight with Wałęsa engineered by the party leader, Kaczyński, in practice, the party had little influence over him and frequently criticized and distanced itself from the government
As I've said before, Kaczyński was playing all sorts of games then. He pretends to be a huge supporter of Olszewski's government, but in reality, he wasn't. If he genuinely was supported by Kaczyński, then he wouldn't have left PC (Centre Agreement) after the fall of his government.