All three have to work together for a lasting fix. Support and buy-in from all three levels increases the likelihood that any initiative or policy will be successful. Politicians can identify the bigger picture and help garner support to improve the chances that an initative will be funded; policy makers provide the regulatory structure and criteria to support and measure the success of the initiative; and public servants are the ones that make it happen.
Of course, I'm a big fan of the public servants!!! But we can't do it alone. No funding, no emphasis, no support, and no criteria equals a failed inititiative, no matter how hard the public servants work--resulting in a lot of frustrated public servants.