They had been for slavery.

They were for free trade.

It never once occurred to him that these things had nothing to do with the local executive and financial administration of Philadelphia.

Supposing they didn't?
What of it?
In Philadelphia at this time a certain United States Senator, one Mark Simpson, together with Edward Malia Butler and Henry A.Mollenhauer, a rich coal dealer and investor, were supposed to, and did, control jointly the political destiny of the city.

They had representatives, benchmen, spies, tools--a great company.