Why did Foster Campbell not overperform in the LA-SEN 2016 runoff?

[America Needs a 13-6 Progressive SCOTUS]

Dems usually do better in runoffs in Louisiana, and Foster Campbell should have been a very strong candidate, being on the states public service commission and representing 1/5th of the state, and being a massive overperformed in those elections. And Reps had a weak candidate themselves who had previously lost US Senate elections under both party labels.

[Arizona Iced Tea]

Dem enthusiasm was in the gutter following Trump getting a trifecta just a few weeks earlier, and the Senate majority wasn't at stake anyway.

[Spectator]

Foster Campbell’s weak performance is pretty stark. He held a very red PSC district if I recall.

[TheElectoralBoobyPrize]

And Reps had a weak candidate themselves who had previously lost US Senate elections under both party labels.

Was he really weak though? He had been the state treasurer, an elected position, for years. His Senate losses can be explained by being the wrong party in each year-he ran as a D in 2004 (bad for Ds overall, but especially bad in the South) and a R in 2008. Also, he's pretty uncontroversial as far as Rs in the MAGA era go.

[MT Treasurer]

Limited resources, too much out-of-state support/resistance cash, lack of a coordinated campaign message/approach, and association with the national party (people tend to forget how much public/vocal resistance there was to Donald Trump in the weeks after his election, well before he had yet to prove himself unpopular as President — whatever pro-life credentials Campbell had were dwarfed by liberal Democrats using the race to strike back against Trump, and not in a smart way).  

The margin was definitely surprising, though.

[JoeyJoeJoe]

(Relatively recent) historical note:  Campbell was the Dem nominee when the party lost the 4th CD for the first time since reconstruction.  When Buddy Roemer left the seat when he was elected Governor in 1987, Republican Jim McCrery defeated Campbell to pick up the seat.