The early nineties conflict between the left and right wings (a bit more complex than simple left and right to be exact) of the Solidarity movement was very nasty. The presidential campaign between Tadeusz Mazowiecki and Lech Walesa in 1990 went racist as the Walesa campaign, run by  Jaroslaw Kaczynski, started asking why Mazowiecki and his advisors were 'ashamed' of their 'nationality' - we're proud of being Polish, why aren't they proud of theirs. Wink wink, nudge nudge.  A number of Mazowiecki's people were indeed of Jewish origin, but most, including Mazowiecki, were not.

The whole thing turned into a sick farce as the Walesa camp was using the one drop rule, and saying that some of Mazowiecki's szlachta ancestors from what is now southern Lithuania and northwestern Belarus might have intermarried with a large group of Jewish converts in the region who were given szlachta status in the eighteenth century.  And so the Mazowiecki people started digging up ancient parish archives and family records.  Absolutely stupid and pointless - those who actually cared about stuff like that would not vote for someone like Mazowiecki, nor would they believe any evidence - they're convinced that every politician they dislike is secretly Jewish.