As senior members of Yemen's opposition prepared to travel to Riyadh yesterday, it was worth asking: who stayed behind?
The question strikes at the heart of Yemen's political turmoil. How can mediation between an entrenched regime and its galvanised opposition occur when opinion remains split, and the endgame is ambiguous?
Some members of the Joint Meeting Parties (JMP), a key umbrella group of opposition forces that has vocally spoken out against President Ali Abdullah Saleh for years, prefer a mediated solution to prevent further bloodshed. Mohammed Qahtan, Ali Mohsen and the defected military general, Gen Ali Muhsin al Ahmar, have welcomed GCC mediation. JMP leaders have accepted Riyadh's invitation to continue discussing possible solutions to the political stalemate.
But some members of the JMP have rejected mediation, insisting instead on an ultimatum that Mr Saleh stand down. Members of the party's youth wing are equally against talks. If the president were to have his way, negotiations would either stall or lead to his departure on his terms - where he and his family are provided amnesty in exchange for ceding power. For this reason, opposition leader Mohammed al Mutawakkil and others have rejected mediation of any sort, on the grounds the JMP would lose credibility for negotiating with the very figure it is attempting to topple.
Whatever Yemen's future holds, a more peaceful one will not be possible without greater internal unity, no easy task in a country with so many competing factions - from separatists in the south, rebels in the north and political parties increasingly at odds.
Yet Yemen's opposition has proven it can find agreement. As Tawakol Karman, a prominent activist, wrote in the Guardian last week: "The country is united in its aim to rid itself of the regime through public vigils and rallies, civil disobedience and slogans instead of tear gas and bullets."
That may be so, and protesters have exhibited tremendous courage despite military violence that has led to over 100 civilian deaths. But political solidarity will have to carry beyond the desire to depose one man. Long-term solutions, from strengthening institutions to addressing corruption, will be critical to forge more common ground.
Though the GCC may provide a platform for discussion and play a decisive role in overseeing a transition of power, the drive will ultimately have to come from Yemenis themselves.