Doubts over US strategy in Syria grew on Wednesday as a key vote in Congress allowing the arming and training of groups fighting against the Islamic State saw a larger-than-expected rebellion among both Democrats and Republicans.

The authorisation requested by the White House – which was presented as an amendment to a finance bill preventing another government shutdown and was strongly backed by leaders of both parties – passed in the House of Representatives by 273 to 156 votes. The Senate is expected to vote as soon as Thursday.

But the decision of 85 Democrats and 71 Republicans to vote no came after six hours of debate that saw concerns raised about the ability of moderate Syrian groups to pivot from fighting president Bashar al-Assad and instead help the US defeat Islamic State fighters known as Isis.

Among those who spoke out against the amendment were Iraq war veterans Duncan Hunter and Tulsi Gabbard, who said the administration had not learned lessons from earlier US interventions in the Middle East.

“We’ve heard this story before. We know how it ends. Look at Iraq. Look at Libya,” said Gabbard, a Democrat from Hawaii. “Clearly, our leaders have not learned their lesson. We must focus on taking out our enemies and investing in our own country here at home.”

The administration plan also came under pressure in the Senate, where a hearing of the foreign affairs committee pressed secretary of state John Kerry to name the un-specified allies in the region who he claims are ready to join the US in air strikes against Isis.

“Later this week we will have more to say about our partners and the coalition,” replied Kerry.

“Not every country will decide that their role is to have military engagement, but every country can do something,” he added.

Republicans on the committee attacked the White House strategy for being ill-thought-out and accused Obama of “exercising terrible judgement” by not seeking broader congressional authorisation.

“Typically you have a coalition in place before you announce it; in this case we have announced one and are attempting to put it together,” said senator Bob Corker

“Do you realise how unserious the things you are laying out sound?” he added. “We know the Free Syrian Army cannot take on Isil, you know that. You talk about a multi-year process, this is going to take decades.”

The Democratic chairman, Bob Menendez, also criticised the administration for not seeking explicit authorisation from Congress for its plans to broaden air strikes against Isis in Iraq and Syria.

Earlier both Kerry and Obama were forced to distance themselves from remarks by the chairman of the joint chiefs of staff suggesting that US ground troops may fight alongside the Iraqi army against Isis.

Pressed on what would happen if the US reliance on Syrian rebels and Iraqi army units was not enough to defeat Isis, Kerry hinted at a possible plan B involving US enemies in the region.

“I am not going to get into hypotheticals but you are assuming that Iran and Syria aren’t going to take on Isis,” he said. “If we are failing miserably, who knows what decisions they might make?”

http://www.theguardian.com/world/2014/sep/17/house-approves-obama-plan-arm-syrian-rebels