THE other day Barney Frank had an op-ed in the Washington Post arguing that the refusal of Senate Republicans to confirm any Obama administration nominee to the Consumer Financial Protection Bureau unless the president adopts their pro-Wall Street stances on financial reform creates a constitutional crisis. If a Senate minority refuses to approve any nominee, regardless of qualifications, until its policy preferences are enacted, it effectively means that the minority can dictate policy to the majority, forcing the government to undo legislation it has passed. Jon Chait agrees that the Republican minority's determination to cripple government as a negotiating tool creates a crisis of governance, but he has a "less moralistic" take on things. After all, the Senate does technically have the power to block administration appointments for any reason it feels like. What's restrained it from doing so in the past aren't formal rules, but a set of informal norms needed to allow the government to function. Increasingly, not just in this case but in many others, Republicans are discarding those norms because they can gain greater advantage, both politically and in terms of enacting their policies, by pushing the rules to the limits and, if need be, paralysing the government. And there's no reason this has to be a one-sided partisan affair.

It's hard to begrudge the opposition party for playing within the rules, not the norms. And the truth is that there's little reason for the opposition to stop playing it this way. Republicans are saying they won't confirm anybody to run the Consumer Protection Agency unless Democrats agree to weaken financial regulations. Democrats could just as easily tell Rick Perry they won't confirm a single economic official unless he agrees to end the Bush tax cuts for the rich.

Mr Chait is right that Democrats could do this. But they won't. Hear me now and believe me later: if Rick Perry become president, Democrats will not stage a large-scale refusal to appoint any of his nominees unless he enacts policies they desire. The Democratic Party is not that kind of political organisation. Like Mr Chait, I don't mean this moralistically; certainly progressives think the party would be more morally praiseworthy if it were more truculent, not less. But structurally, Democrats lack the unity needed to enforce a boycott of this sort. The simplest reason for this is that the Democrats draw their electoral margins from poor and working-class voters, but depend (like the Republicans) on financial support from the wealthy and from business. This splits the party down the middle in a way you don't see with Republicans. You're always going to have defections by major Democratic politicians, be it the centrist "blue dogs" on a range of business-related issues, or the otherwise reliably liberal Chuck Schumer on issues related to the financial industry.

There are other reasons why Democrats lack the pugnacious unity required to stage boycotts like those the Republicans routinely engage in. Some of it, I think, is characterological: in terms of attribution theory, conservatives are more likely than liberals to believe in the "just-world hypothesis" that good things happen to good people and bad things happen to bad people, and correspondingly (since everybody considers themselves good people) to attribute responsibility for problems or failure to someone else while taking responsibility for success themselves. (In the terminology of John Jost, a psychology professor at NYU, conservatives have a stronger affinity for "system justification", which contributes to stances such as global-warming denialism.) This makes conservatives better bargainers than liberals. In conflict situations, conservatives are more likely than liberals to be comfortable ascribing all blame to the other guy, while liberals are more likely to assume they must bear some of the blame themselves and to reach for compromise.

But the upshot of higher levels of Republican unity and toughness is that they are better than Democrats at shifting informal behavioural norms to their advantage. Procedures that aren't codified can be altered relatively easily by a highly committed, unified minority. The defence of a disunited majority from such coordinated goalpost-pushing lies in firm and explicit rules. It remains a mystery why more Senate Democrats did not see the use of altering the body's rules while they held a commanding majority in 2009-10, to ensure it could continue to function in the face of a minority party bent on paralysing it. Then again, it's also a mystery why they have so meekly accepted the Republican "new normal" of constant filibusters and confirmation boycotts. Perhaps they blame themselves.