I watched it once a couple of years ago and I thought it was socialist propaganda even at that time. I’ve never watched it since.
It was so political that it wasn’t even funny. It deals with unionized city employees being harassed by evil Republicans and something that sounded to me like a Scott Walker governor, so what more do you need to know about it?
It should be called “Perks and Reparations”
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It was definitely pro-government and pro-more government. Leslie Knope, the lead character is in love with government and with running things. If you want to call that socialist you can, though it's not like they were advocating the abolition of private property.
But I never saw any indication that the employees were unionized at all. Or much sign of a governor, though one might have appeared in an episode or two. There was plenty of satire of ignorant politicians, but I wouldn't jump to assume that they were all Republicans.
The show definitely did have a political bias and ends with the lead character and her husband holding high office as Democrats, but the main character and her attitudes were also (lightly) satirized, and her libertarian, anti-government boss often ended up being right.
Mostly, it was just another sitcom. Liberals loved it, but I don't think many people being were converted to their views by watching the show. They just took it as entertainment.