Imagine no campaign donations. It's easy if you try.

Imagine, for a moment, that you didn't need to raise money to run for office, that the government would pay you to run. Who would that help? Would it encourage more moderate candidates, who are usually pressured out of nomination contests by party money because they don't stand for anything? Or would it enable the extremists, whom are normally de-funded due to concerns about their toxic views?

Well, we actually don't need to imagine. Arizona and Maine had just such a system in place for state legislative elections during the last decade. So Michael Miller and I collected roll call votes from those states and compared those who first got elected through "clean" funding with those who achieved offices through traditional funding methods. We report the results in our new paper "Buying Extremists," which we're presenting next week at the meeting of the Midwest Political Science Association. Here's a summary of what we found:

• Clean-funded legislators were more ideologically extreme relative to their districts and parties than traditionally-funded legislators were.
• The extremism difference faded with time, with clean-funded legislators becoming socialized after several sessions to mirror the views of their traditionally-funded colleagues.

These findings suggest that it's the more ideologically extreme candidates who take advantage of clean funding to run for office. Under the traditional funding system, party donors function as gate-keepers, reducing the power of extreme candidates by channelling money away from them. Take away the gate-keepers, and it's the extremists who break through, contributing to the polarization of the legislature.