Republican politician John McCain is not often called a 'softie'. But late last week, a man brought a package of marshmallows to a citizens' consultation hour with the senator in Tucson, Arizona. "This is what I think of Congress," the man shouted. "Those are marshmallows." He said the people's representatives ought to show some backbone and reject an intervention in Syria. "Why don't you listen to the people and stay away from it?" the man asked. "It's not our battle."

When it comes to Syria, nothing illustrates the dilemma US President Barack Obama is experiencing better than John McCain's current problems. McCain, who lost the presidential elections to Obama in 2008, used to be at the forefront when it came to pushing for the US army to participate in armed conflicts abroad - and he generally had the support of his voters in his home state, conservative Arizona.

In the case of Syria, McCain has been calling for a firm intervention against Assad's regime for months. He says the limited intervention which the Obama administration plans as punishment for the chemical weapons attack on August 21 doesn't go far enough. But at the meeting in Tucson, applause roared when another member of the public educated the senator: "We didn't send you to start a war. We sent you to prevent the war."

Tired of war

US Americans are tired of war - and the fatigue stretches across all parties. In a late August survey by Pew Research Institute, 48 percent of the interviewees were against an intervention in Syria, only 29 were in favor.

In 2008, Obama came to power with a pacifist message. Now, he finds himself having to gather support for yet another military intervention in the Middle East. In recent days, his advisors and members of the administration have laid out in television interviews and in speeches why the US can't look on while Bashar al-Assad gases innocent civilians. The White House says there is proof that the regime used sarin gas to kill more than 1,400 people in an attack on Damascus' suburbs.

On Tuesday evening, Obama will address the nation. But whether that will be enough to convince Congress to give him the authorization for an attack is far from clear. Observers say the chances are relatively high for approval in the Senate, which could already vote yes in its plenary session this Wednesday. But over the weekend, it looked like there was a tendency that the House of Representatives would vote against an attack. On its website, broadcaster CNN on Sunday counted 25 "yes" and 143 "no" votes. The remaining representatives were still undecided.

As a Democrat, Obama is facing a two-fold problem, said Mike Lux, the head of Progressive Strategies, an organization that advises left-leaning groups. "Republicans who would be most likely to support a military strike, don't trust Obama. And the people who like Obama (i.e. Democrats) don't like military intervention," Lux told Deutsche Welle, adding that that made for an unusual alliance between left-wing Democrats and right-wing Republicans.

Cross-party rejection

You have to go beyond party politics to find an explanation, however, said Ronald Brownstein, who has written a book about the polarization in Congress. "We are seeing something larger than Obama, Congress or the US," Brownstein told Deutsche Welle.

War fatigue be observed throughout the western world, said Brownstein, adding that this was illustrated by the vote in the British parliament, whose members refused to give Prime Minister David Cameron approval for an intervention. Independent of the actual situation in Syria, the costly and deadly military interventions in Afghanistan and in Iraq had shattered people's trust in the need to ntervene, Brownstein explained.

That's why it was not enough to explain the Republicans' stance with their rejection of Obama, said Brownstein: Those within the party close to the Tea Party movement, he said, combined isolationist tendencies with a rejection of everything that could potentially strain the budget. Their leader in the Senate is Rand Paul. Last week in the Foreign Affairs Committee, it was the populist Kentucky politician who was leading the resistance against the resolution which would authorize the attack on Syria. "McCain no longer speaks for the majority of the Republican Party on foreign policy," was Brownstein's summary.

While McCain was behind a more aggressive wording of the Syria resolution before the Foreign Affairs Committee approved it last week, the new draft calls for more support of the opposition. In a local radio interview meanwhile, McCain preferred to stress that American troops on the ground in Syria are not an option - and threatened Obama with impeachment proceedings should he attempt any such escalation.