Jon Chait says that what progressives need is more primary challenges against wayward members of the House and Senate. As I noted in a Daily Beast article making a similar argument there’s not even a particular need for the challenges to be successful:
But there are at least two senators who haven’t given the White House a peep of trouble recently — Specter and Gillibrand. This may come as a bit of a surprise. Gillibrand was one of the most conservative House Democrats and Specter was, though not very conservative for a Republican, still more conservative than every single Democratic senator. Now, though, they’re loyalists. And this is no coincidence — both senators are facing possible primaries and both know perfectly well that their records will provide plenty of grist for a challenger’s mill. Consequently, they’re determined not to provide any new instances of deviation. Obama’s inability to clear the field for these incumbents is actually critical to his ability to get them to vote for his agenda. In other words, if avoiding primaries is really the test of Obama’s political strength, his success in changing policy may depend on him finding some more opportunities to fail.
Of course one problem here is that raising the money to mount a credible Senate primary can be difficult. If you represent a far-right ideological faction slavishly devoted to the interests of high-income Americans, this problem can be finessed. It’s somewhat more difficult to conjure up tens of millions of dollars to advance the interests of Medicaid recipients.