Landrieu is likely to face a tough race in the conservative, increasingly Republican state.
A number of House Republicans are thought to be interested in the seat. Rep. Bill Cassidy (R-La.) has $2 million in the bank, by far the most in the House delegation. Rep. John Fleming (R-La.) has $480,000 cash on hand but is carrying nearly $250,000 in debt, while Rep. Charles Boustany (R-La.), who faced a tough race from former Rep. Jeff Landry (R-La.), has $190,000 in the bank. Landry, a Tea Party favorite who hasn't ruled out the race, has just $67,000 left, with $22,000 in debt.
While a contested primary often benefits the other party, because of Louisiana's unusual election rules all candidates run on one ballot in the November election, and the top two vote-getters then have a runoff in December, making the race more expensive for all candidates and putting a premium on early fundraising for the candidates.