As long as I’m focusing on U.S. politics today. . .
Charlie Cook has a set of very interesting analyses of loyalty to leadership among Democrats and Republicans. While Democrats who live in safe districts are more likely to vote with Pelosi than Democrats from marginal districts, the opposite is true among Republicans. Marginal district Republicans are much more likely to vote with Boehner than Republicans from safe districts.
This pattern is likely explained by primaries and the unusual disjuncture between the hardcore Republican base and the House leadership. Members from safe districts in both parties have a huge incentive to pay more attention to their primary rather than general election electorate. While moderation is rewarded in the general election, it’s all about the base in a party primary.
As a result, Democrats from safe districts have no problem casting solid left votes. Notice that the major Democratic defection from President Obama was on trade, where he lost Pelosi’s support and was at odds with the Democratic union and left-wing base.
The Republican conservative base is hostile to efforts by Boehner and McConnell to concede ideological points in order to govern. Ted Cruz’s attack on Mitch McConnell was an applause line at last night’s debate! So Republicans from safe districts are more likely to rebel against their party’s leadership. In contrast, marginal district Republicans want their party to look reasonable and able to make the government function so they vote with Boehner.