CNN 100: The winner of the run-off will likely win the election.

Editor's Note: In the final 100 days before Election Day, CNN has been profiling one race at random each day from among the nation's top 100 House races, which we've dubbed "The CNN 100."

Read the full list here . Today's featured district is:

Louisiana 03: Rep. Charlie Melancon is running for Senate and leaving behind an open seat.

Primary: August 28, 2010
Location: Houma and Thibodaux, the eye of the Katrina storm.
Days until the election: 33

This seat, which has opened up because three-term Democratic Rep. Charlie Melancon is challenging GOP Sen. David Vitter, looks like it is headed into the win column for the GOP. The twist here is that we won't know who the Republican candidate is until October 1, when the GOP holds a run-off between Iraq vet and businessman Jeff Landry and former state House speaker Hunt Downer.

This is the only seat in the state that isn't already in Republican hands, and despite running unopposed in his party's primary, Ravi Sangisetty, the Democratic candidate, has a long way to go with the conservative-leaning voters in the district in order to win.

The GOP primary has been brutal, with the candidates sharing much of their ideology but nevertheless attacking each other fiercely. And it hasn't been cheap - each Republican has spent over a half a million dollars fighting to get the party's nod (and that is a lot in this part of the country).

Sangisetty has campaigned as a "pro-life, pro-gun conservative Democrat." He ran unopposed in the state's Democratic primary, and has the added benefit of being Indian-American in a state that has already elected an Indian-American - popular Gov. Bobby Jindal - to the highest office.