As for whether voters are more ideological or not, it seems that, regardless of how ideological the candidates are, when voters reject senior congressmen they are voting along more ideological lines. A challenger candidate can only justify his candidacy based on ideology, since seniority is so important in terms of bringing money in, so can’t you really say that, regardless of the ideological extremism of either the candidates or the voters, voters are making an ideological decision when they reject a senior congressman? Obviously there could be other factors like scandal, etc, but all things being equal.

To use a specific example, my hometown district in South Texas just voted out Solomon Ortiz, who had been our congressman for 27 years. The district is pretty blue collar and undeveloped, and probably more dependent on the money that Ortiz brought in than the typical district, so there was definitely a strong incentive to consider seniority in voting. He was also a pretty moderate Democrat, and his challenger was a relatively inoffensive (especially for this election cycle) Republican. I’m sure on any kind of partisan index, the two would not be too far apart. Still, even though there was not a gaping ideological division between the candidates, wouldn’t ideology still be the sole motivator for voting against him, considering the very concrete downside that losing that funding represents?

I’m not sure, however, that voters are voting along more ideological lines than previously. Part of the problem is that they can only vote for one of two candidates – if both candidates are drawn from the extremes of the party, it might appear that voters have become more ideological even if their preferences haven’t changed.

I assume by “patronage” you mean voting on the basis of what the Senator/Representative has brought to the district – i.e., more goodies (aka pork). Is that right?