How important is the writing sample for PhD application in Political Economy I'm planning to apply for US's PhD program in Political Economy, and a writing sample of maximum 20 pages is part of the application requirements. The problem is I don't think that I have any recent high-quality writing to submit. I didn't write a thesis for the B.S. as my university didn't have that kind of requirement. I've been working for an international research center, but most of my works are mostly applied econometrics and I didn't really get to do any writing.

Bottom line is my writing sample will most likely be the weakest link in my application. If so, how bad will it hurt my chance? Is there anyway to get around this?
Of course this can vary from one department to the next, but in the humanities, the writing sample is generally considered very important.

According to the Department of Politics at Virginia Tech,


  Your writing sample is the most important part of your application.


Political science types are likely to weigh the writing sample more heavily than economics types, at least according to this political economist. 

If you do not have a thesis, you should at least have a relevant term paper or similar paper from your coursework that you can use as a starting point. Your writing sample should demonstrate critical and analytical writing (not merely descriptive).