She was nominated to the office by Governor Jeb Bush in February 2003 to replace Frank Brogan, who resigned to become president of Florida Atlantic University.

In 1994, when Orange County chairman Linda Chapin announced she was not seeking re-election, she failed to convince Jennings to return to Orlando and campaign for the office herself.

Instead, she remained in Tallahassee to be elected by her Senate peers to be president of the Florida senate—the only person to have held that office for two terms, from 1996 to 2000.

In 2000, legislative term limits came into effect, having been instituted by a constitutional referendum taken several years earlier.

Jennings endorsed former Massachusetts Governor Mitt Romney in the 2008 presidential primary election.