Why did Al-Wifaq agree to participate in royal dialogue in Bahrain

My chief Bahrain correspondent wrote this:  "Just so that u know, Alwefaq agreed to participate in the dialogue - said won't lower demands and if demands are not taken seriously it will withdraw. My guess is that the past week alwefaq was pressured by the UK and the US to enter the dialogue. Al wefaq met for example with the British Embassy this week. They must have discussed this. That is why they were hesitant to say they will not participate although in every speech they gave, they said that the dialogue was not serious. I think the existence of this so called independent commission played a huge role in their decision. Alwefaq probably didn't want to announce that it will participate until they could show their constituents that there is another player in the room. Obviously their constituents are very angry at their decision. But I think it does not matter. In the end, the dialogue will fail and the protestors will keep protesting. Just as in Yemen, the split between what the protestors want and what the opposition is doing is becoming bigger. Opposition knows this but somehow feels they need to go through the motions - probably to portray to the west that they are "moderate" and "reasonable." What's funny about this is now alwefaq and waad, the two strongest opposition groups with the most support r going against what their constituents want but then you have smaller groups such as leftist Altajamou' alwatani aldimoqrati (national democratic assemblage) boycotting the dialogue."