[citation needed] In the following years Findley served in the Ninth through Twelfth General Assemblies and on the Supreme Executive Council.

[6] Findley was also a major opposition voice[7][8] in the Pennsylvania convention that ratified the federal Constitution and was a signer of the Minority Dissent.

A Jeffersonian Republican, Findley opposed the financial plans of Federalist Treasury Secretary Alexander Hamilton and supported the cause of states' rights.

[12] After declining nomination to the Sixth Congress, he was elected to the Pennsylvania State Senate because he allowed his name to be placed on the local ticket to rally western support for Thomas McKean's campaign for governor.

Elected to the Eighth Congress, he served through the Fourteenth, the turbulent years of the Burr conspiracy, the embargo, and the War of 1812 as a strong supporter of Thomas Jefferson and James Madison.

He was known as "The Venerable Findley," and because he was the senior representative in years of service, he was in 1811 designated "Father of the House", the first man to be awarded that honorary title.