“How is legislative pay a liberal/conservative issue?”
Jindal, posing as a strong Conservative for the people of Louisiana, issued the campaing pledge while running for Governor to not allow a legislature pay raise to take effect while they were in office.
He didn’t make such a campaign pledge or even a promise while running for governor. It was part of his “plan”:
http://forgotston.com/wp-content/uploads/2008/06/jindalforgov.pdf
However, he also planned to reform Louisiana government and improve schools. He needed to make a compromise to save his whole agenda. No big deal.