Darnell unsuccessfully sought the position of Speaker of the Senate against incumbent John Shelton Wilder in 1986.

He lost re-election in 1992 but successfully defeated incumbent Secretary of State Bryant Millsaps and served in that position until 2009.

[3][5][2] Riley announced in 1970 that he would seek the Democratic nomination for a seat in the Tennessee House of Representatives from the 67th district to succeed Frank J. Runyon.

[15] In 1975, Riley was selected over state Senator Doug Henry to succeed Representative John Hicks as chairman of the Fiscal Review committee.

[16] Riley announced in 1980 that he would seek the Democratic nomination for a seat in the Tennessee Senate from the 22nd district to succeed Halbert Harvill.

[28][29] Wilder later appointed Joe Nip McKnight to replace Darnell as chairman of the Transportation committee.

[31][32] Darnell won the Democratic nomination against Millsaps on November 19, and was elected as Secretary of State on Tennessee General Assembly on January 13, 1993.