Short of that, the system can be bent to deliver reforms under capitalism, as we know from the struggles of workers in the 30's, blacks in the 60's, and women and gays in the 70's and 80's.
But in each case these movements had to take to the streets to complement the electoral activity which enshrined their demands in legislation.
I wouldn't counterpose one to the other. Both forms of mass activity are necessary. No legislation, no rights. No demonstrations and other forms of "extra-parliamentary" action, including civil disobedience, no legislation.
The Republican right has taken to the streets. It may be slowly dawning on the liberal left in and around the Democratic party that unless they likewise begin to pressure the Obama administration by mobilizing their forces outside of the electoral system, meaningful reform is beyond reach.
It's too early to throw in the towel, but if there is no more motion on the left over the next year and the initiative remains with the the right, there'a real possibility the "centre" will shift back to the Republicans in the midterm election.