There is an interesting essay by Martin Pickup entitled, "Matthew's and Mark's Pharisees" in Jacob Neusner and Bruce D. Chilton, eds., In Quest of the Historical Pharisees (Waco: Baylor University Press, 2007), 67-112. As part of his chapter, Pickup provides an analysis of the Pharisees in Jewish society.
Especially within Mark's gospel, the Pharisees are not presented as having any sort of political power or authority - or even 'holding religious office' (71). Throughout the narrative they must join together with the Herodians in trying to take care of the Jesus situation. This means, I believe, that while they are not happy about Israel's position of exile under the Roman government they nevertheless must find ways to work with the system in order to get what they want. It is a peculiar situation which reflects much of our world today - proving again my assertion that we are not as far from the Pharisees as we would have ourselves believe.
Notice that this is evident in that the Pharisees 'have no direct involvement in Jesus' arrest and trial' (71). Somehow, Jesus' most constant source of criticism and opposition fade away when the story arrives at its climax. This could be because Jesus and the Pharisees were really about the same idea - the restoration of Israel - although they differed greatly in their interpretation of Torah. The sacrifice of atonement was never questioned throughout the gospel, although additional laws of ritual were often at the forefront of controversy.
Further, although they are a very visible sect of purity and righteousness, the Pharisees are not presented as having any control over the synagogues (cf. 71). Their influence seems to come from their visible dedication to Torah and purity, often initiating the right discussions among the right people at the right times in steering the ship of Israel's restoration. But then they are able to get out of the way of the political and military machine which they will denounce as standing in the way of Israel's vindication.
The Pharisees' power seems to come from their voice - the ability to rouse public opinion and focus on matters which they deem important for the nation. This is not too far from many evangelicals, who have used the fellowship of the saints as a means for advancing various agendas which may or may not reflect sound biblical doctrine. And this is done to the division of the church, for it draws lines which make it quite difficult to accept a brother or sister in Christ through the haze of activism. And, when the need for true atonement arrives, they are the first ones fading into the woodwork.