Washington - US lawmakers began work on Monday on their version of an authorisation of the use of military force in Syria, worrying that President Barack Obama's draft could open the door to possible use of ground troops or eventual attacks on other countries.
Obama's proposal, released on Saturday by the White House, authorises the president to use the armed forces "as he determines to be necessary and appropriate in connection with the use of chemical weapons or other weapons of mass destruction in the conflict in Syria".
It also explicitly allows military action to deter or prevent the transfer of those weapons into or out of Syria.
The Obama administration has accused the Syrian government of killing more than 1 400 people, many of them children, in a sarin gas attack near Damascus on 21 August. Syria has blamed the attack on rebel forces.
Although the authorisation's focus is on the use of chemical weapons against Syrian President Bashar Assad's opponents in the country's 2½-year-old civil war, it did not set a time limit on any military action or confine it to Syria or spell out other limits clearly enough for many US lawmakers.
Democratic Senator Robert Menendez, chairperson of the Senate Foreign Relations Committee, and Democrat Harry Reid, the Senate majority leader, were conferring on Monday on the text of the Senate's version of a revised authorisation, a Senate aide said.
The committee could begin debate on a Senate version of the bill on Wednesday afternoon, with an eye toward bringing it to the full Senate for debate next week.
The House of Representatives and the Senate return from a summer break on 9 September. Both chambers would have to approve the authorisation, and it was unclear whether the Obama administration has the votes.
The authorisation of the use of military force against al-Qaeda signed into law in September 2001 by Republican President George W Bush has been used to justify a dozen years of US counterterrorism efforts by both Bush and Obama, from the war in Afghanistan to warrantless wiretapping and drone strikes - with little congressional oversight.
"The resolution that they are presenting right now is so open ended, I think even people who are sympathetic to the administration might have trouble supporting it," said Representative James McGovern, a liberal Democrat from Massachusetts.
"The broad authority the president asked for creates lots of concern with me and others," Republican Senator Roy Blunt of Missouri told reporters after a three-hour classified briefing for lawmakers on Sunday.
"And I think that that's to be narrowed in the next week," he said.
Some legal analysts said Obama's authorisation for the use of military force (AUMF) request as written could open the door to military action not just against Syria, but against other countries if they were deemed to be connected to the use of chemical weapons within Syria.
"The proposed AUMF focuses on Syrian WMD but is otherwise very broad," Harvard University law professor Jack Goldsmith, a top Justice Department official in the George W Bush administration, wrote in an online commentary in a widely read legal blog called Lawfare.
Despite the White House's repeated assurances that US action in Syria would not involve "boots on the ground," many lawmakers want any authorisation to specify that no US forces would be sent into Syria.
Most said that, if there is any military action at all, it must be restricted to missile strikes into Syrian territory or aid to rebels fighting to oust Assad.
Democratic Representative Chris Van Hollen of Maryland said he wanted an authorisation that spelled out that no US forces would be sent to Syria. He also wanted it to be very clear that after an initial strike, more force would be used only if the Assad government were to again employ chemical weapons.
"This is not a question of trusting the president," he said. "I trust the president. This is an issue of what authority Congress decides to grant ... In my view that grant of authority should be very circumscribed, to the very narrow purpose for which it's intended."
Harvard's Goldsmith said the authorisation as drafted by Obama could let him use any element of the US armed forces and does not contain specific limits on the identity or location of targets.
He wrote that the authorisation does not limit Obama's action to Syrian territory.
"The phrase 'The President is authorised to use the Armed Forces of the United States as he determines to be necessary and appropriate' would include authorisation for ground troops, should the President decide they were 'necessary and appropriate,'" Goldsmith wrote.