WASHINGTON (AFP) - It comes to every US president and now looms relentlessly for Barack Obama: the moment when he must shoulder the lonely duty of his office and take a fateful decision on national security. After weeks of in-depth meetings and drawing counsel from top advisors, Obama will eventually have to make up his mind on whether to send thousands more troops into the cauldron of Afghanistan. Its really coming down to him, said Julian Zelizer of Princeton University, author of a forthcoming book on US foreign policy. This is a lesson that presidents always learn when dealing with military affairs. Obama has launched an exhaustive and collective review of Afghan policy within his national security council. But the constitutional authority vested in the president means the buck stops sooner or later with the commander-in-chief. It is not a collective decision. Abraham Lincoln said there was only one vote that counted in his cabinet, said David Rothkopf, a visiting scholar at the Carnegie Endowment for International peace. There is only one vote that counts at the national security council, added Rothkopf, author of a history of the presidents top foreign policy body. Signs are mounting that Obama may be nearing a critical point in his deliberations. He said last week he would complete the process in the coming weeks. Secretary of State Hillary Clinton told CNN: Weve done a thorough job of analysis, and now were moving into the decision phase. Obamas stakes may match or even exceed those faced by other recent presidents, like Lyndon Johnson who agonized over the Vietnam War, or Bill Clinton who worried whether to intervene in Bosnia. Soaring expectations at home and abroad may be on the line in a decision many observers feel could drain the reforming momentum from Obamas presidency should it go wrong. Obamas own audacity, in refusing to temper high hopes and raising the stakes by likening himself to political greats like ex-president Lincoln and even his recent Nobel Prize may also stoke the pressure. Not to mention the burden of the lives of any of more than 60,000 US troops at war, the tens of thousands who may follow, and unknown numbers of Afghans. Critics accuse Obama of undue delay but the long wait may reflect the fact the president has few palatable options in the eight-year war. Obama has conducted five extended briefings with top military, political, diplomatic and intelligence aides and has another this week. Official photos from the secure White House Situation Room reveal intense sessions, with Obama in deep conversation with national security aides. I think the president has been extremely skilful in probing and asking all the hard questions, Secretary of State Hillary Clinton told CNN. Broadly, Obama, who has already ruled out withdrawing troops, has three options unless he can conjure another that few analysts have considered. He can go all-out with an Afghan counter-insurgency strategy advocated by war commander General Stanley McChrystal, which requires at least 40,000 more troops. An approach pushed by Vice President Joe Biden would see more targeted tactics, focusing on destroying Al-Qaeda in Afghanistan and especially Pakistan, but eschewing a full-scale counter-insurgency. A middle path, attractive to top Democrats in Congress, might see thousands of troops being deployed only to train the Afghan army. Obama backers view his thorough analysis of US options in Afghanistan as a break from the gut-level decision-making of the Bush administration. That NSC allowed power players like vice president Dick Cheney and secretary of defence Donald Rumsfeld to freelance, with disastrous results in Iraq. The Obama NSC has reined in the presidents vaunted team of rivals cabinet of heavyweights, despite their healthy egos and political power bases. It also reveals Obamas own disciplined, no drama self-image as a leader, who probes every angle of a problem. But is there a point when deliberation becomes procrastination? There is a certain time period when it looks like a president is being deliberative and thoughtful, said Zelizer. After that time period, it looks like a president who cant make tough decisions, either way the kind of Jimmy Carter syndrome. Rothkopf added: deliberations can go on too long I dont think they have yet.