[kesg]

The reason Republicans are difficult to reach on weekends is that a disproportionate number of them work on weekends, frequently at jobs they've created. They are also more likely to screen their calls or have unlisted numbers.

I think the real problem is that both sides are out more on weekends -- for whatever reasons -- and therefore you don't get as representative a sample as you do on weekday evenings (when more Americans are likely to be at home during the evening times that most pollsters call).

[andy58-in-nh]

I think the real problem is that both sides are out more on weekends

That's true. Democrats and Independents who are out on weekends are likely to be homeowners and/or workers as well. That would certainly create a less representative sample.