The announcement on May 13 that Lakhdar Brahimi was resigning as the United Nations and Special Arab League envoy to Syria came as no surprise. The veteran diplomat had been considering doing so for most of his time in the post (he said a year ago that he thought about it every day), and the conflict has continually worsened despite his mediation. It was clear almost as soon as he accepted the role in August 2012 that his efforts would end in failure.
After all, his predecessor Kofi Annan, who resigned after just six months, described the job as "mission impossible". Brahimi was only slightly less pessimistic, saying at the outset that it was "nearly impossible". Likewise, UN Secretary General Ban Ki-moon said recently that Brahimi - "one of the world's most brilliant diplomats" - faced "almost impossible odds". To say they were managing expectations is a major understatement.
Brahimi can be criticised for pursuing Annan's failed policies rather than offering anything new, but this wrongly implies that the formula itself was wrong. The main aims of Annan's Geneva I conference in June 2012, and Brahimi's follow-up conference earlier this year, were to agree a ceasefire, then form a transitional government comprising both regime and opposition elements. What other viable diplomatic option is there?
The obvious stumbling block was not clarifying what role, if any, Syrian President Bashar al-Assad would have in such a transition. The opposition says there is no solution with him, while the regime says there is no solution without him.
However, if Assad's role had been made clear, the Geneva communique would never have been agreed to in the first place. This did not stop the regime from accepting the communique as a precondition for participating in the conferences, then flouting it by refusing to discuss a transition.
The crux of the problem is that the effectiveness of mediating the Syrian conflict is entirely reliant on cooperation between its opponents, both domestic and foreign. This prospect, which was never realistic, is more remote than ever. As Ban said recently, Syria, the Middle East and the international community are "hopelessly divided".
A few names are being floated as potential successors to Brahimi, but it would be a brave - or delusional - person who thinks he or she can take on 'mission impossible'.
In addition, negotiations need to be more inclusive and representative, but this is not just a matter of inviting Iran and a broader range of Syrian opposition groups. In terms of the latter, major political and armed factions have refused to participate, or honour any agreement that is reached within a framework they reject or were not involved in.
Whoever replaces Brahimi is even less likely to succeed. Tensions between the West and Russia have been greatly exacerbated by the deepening crisis in Ukraine, which directly and negatively impacts the chances of cooperation on Syria.
String of recent regime successes
On the domestic front, increased rebel infighting, and a string of recent regime successes on the battlefield (made possible by foreign fighters and military supplies) has boosted Assad's confidence and made him even more belligerent.
Having said in April that he believes the "active phase" of the war will be over by the end of 2014, the prospect of his regime engaging in any meaningful diplomacy is wishful thinking. The regime is now "saying that we're winning, and that there's no need to talk," Brahimi said in May.
This is evidenced by the staging of elections in June that will be neither free nor fair, whose conditions and restrictions make Assad's victory a foregone conclusion. Brahimi's criticism of the vote as an obstacle to a negotiated solution earned him the wrath of the regime, which seems glad to see the back of him.
"Many mistakes were committed during Brahimi's term, including his interference in Syria's internal affairs, for a mediator does not interfere in sovereign affairs of any state," said Syria's ambassador to the UN, Bashar al-Jaafari. A mediator's role is to be involved - if this is interpreted as interference in sovereign affairs, it seems the regime will only accept an envoy whose role is purely ornamental.
A few names are being floated as potential successors to Brahimi, but it would be a brave - or delusional - person who thinks he or she can take on "mission impossible".
Meanwhile, developments are emerging that may signal a shift from UN-led international efforts towards a more regional role, particularly with regard to Middle Eastern powerhouses and long-time rivals Iran and Saudi Arabia.
In May, Tehran offered a proposal that is "worth discussing", according to Brahimi, who has briefed the UN Security Council about it. Iran says it is willing to seek the postponement of presidential elections in Syria if the Council endorses the plan.
It reportedly entails a ceasefire, the withdrawal of foreign fighters, a national unity government, a constitutional review aimed in particular at reducing presidential powers, and UN-supervised presidential and legislative elections.
This sounds reasonable, but is subject to numerous stumbling blocks. Foremost among them are the two that have stymied the Geneva process: Assad's role (if any) in a national unity government, and more basically, the regime's unwillingness to even discuss a transition.
The other big questions are whether Assad would be willing to put on hold elections he is certain to win; if he would agree to a reduction in presidential powers when he sees himself as the country's legitimate president; whether his regime would accept free and fair elections; and if Iran is referring to foreign fighters on both sides of the conflict, not just those fighting against Assad.
"They must mean also Hezbollah and the Iraqis and their own," said Brahimi.
In tandem with this proposal, there have been overtures between Tehran and Riyadh. On the day that Brahimi announced his resignation, the Saudi foreign minister expressed his country's willingness to negotiate with Iran on "any differences" and that his counterpart had been invited to the kingdom. The following day, Tehran welcomed the invitation and the offer of talks. Syria would undoubtedly be high - if not top - on the agenda.
However, there is a sense of deja vu about this. Both countries traded conciliatory messages after the 2013 election of Iranian President Hassan Rouhani, but the warm words and expressed desire for improved ties came to nothing. This is hardly surprising given the numerous and major regional issues dividing them, including Iraq, Bahrain, Lebanon, Iran's nuclear programme and of course, Syria.
Rouhani has made good on his pledge to maintain "unwavering support" for the regime, which "no force in the world can shake", adding that Assad will emerge "victorious". Meanwhile, Saudi Arabia - one of the principal backers of the revolution - has said it "cannot be silent" about Tehran's intervention. Although both countries are key to resolving the Syrian conflict, there is no sign as yet that either is willing to shift positions.
"The more a conflict goes on, the more difficult the political solution will be to achieve," said Brahimi. He is right. That was said almost a year ago, and since then the prospects of a negotiated settlement for Syria have only receded.
Sharif Nashashibi is an award-winning journalist and analyst on Arab affairs. He is a regular contributor to Al Jazeera English, Al Arabiya News, The National, The Middle East magazine and the Middle East Eye.
The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.