WASHINGTON  - After months vowing to get US troops home from Iraq, Barack Obama has succumbed to the war's political entanglements, struggling to explain his plan in the light of recent security gains. More than five years after the US invasion, the Iraq war is now enmeshing not only the Bush administration which started it, but both men fighting to inherit it, Democratic White House hopeful Obama and Republican John McCain. Obama is torn between a vow to end the war, which underpinned his win over Democratic foe Hillary Clinton and Republican claims his plan invites US humiliation, would delight terrorists and waste gains bought in American blood. Under rising Republican pressure, Obama last week said he may "refine" his policies after meeting US commanders in Iraq on a trip expected this month. But hours later, he hurriedly called a second Press conference to insist he had not made the "flip flop" on Iraq that many observers are expecting, as he retools his message for the political centre ground. Obama says he can get most US combat troops home within 16 months, leaving behind a smaller force to fight terrorism and protect the US embassy. He wants to redirect resources to Afghanistan, where more US and coalition troops were killed last month than in Iraq. "The needle that he has to thread is staying on message and linking McCain to Iraq inexorably, while taking half a step backward from the most forceful enunciations of his desire to get out," said analyst Justin Logan, of the Cato Institute. The McCain campaign relished Obama's struggles, claiming he had finally endorsed his rival's strategy on Iraq. "For long time, Senator Obama said let's get those troops out as quickly as we can, regardless of what's happening on the ground," said independent Senator Joe Lieberman, a top McCain surrogate, speaking on US television Sunday. "John McCain had the guts to say in 2003 to the Bush administration ... 'our policy in Iraq is failing. We need more troops,' when everybody else was saying 'pull the troops out'," Lieberman told ABC television. "Now his policy is working. Iraq is succeeding. And Senator Obama has to deal with that inconvenient truth." Meanwhile, Obama partisan Senator Jack Reed, an expert on defence issues, insisted that the Illinois senator's underlying message on Iraq is unchanged. "Senator Obama is outlining a strategy to redeploy our forces out of Iraq. Senator McCain has a strategy of staying there indefinitely. That is the key, significant strategic difference," Reed said. While he enjoyed his rival's struggles, McCain, despite being an early critic of Bush war policy, and early advocate of the surge, is still in a dicey spot. His reluctance to pull US troops out quickly appears at odds with much of American public opinion, and brackets him with the highly unpopular President George W Bush. Bush and McCain's theory of Iraq has been "we will stay there indefinitely and one day, perhaps the Iraqis will wake up and decide that they're willing to work through their differences and reconcile," said Susan Rice, a top Obama foreign policy aide. "Barack Obama's view is that that has not succeeded five years in, and moreover, it's unsustainable." According to the latest CNN/Opinion Research poll, 30pc of Americans favour, and 68pc now oppose the war. Sixty-four per cent believe US troop numbers should be cut, compared to 33pc who think they should remain the same.