Democrats and Republicans have expressed cautious optimism about the chances of raising the US debt limit by Tuesday and averting possible default. Republican Senate leader Mitch McConnell said there was "a level of seriousness with the right people at the table" as talks continued. Senior Senate Democrat Richard Durbin spoke of "a more positive feeling". In a sign of the level of anxiety over the issue, troops in Afghanistan asked Adm Mike Mullen if they would be paid. The admiral, who as chairman of the Joint Chiefs of Staff is on a visit to southern Afghanistan, said he did not know whether that would be the case if the US fails to raise the $14.3tn (£8.7tn) limit by 2 August. Democrats and Republicans have so far rejected each others' proposals for cutting spending and raising the debt limit. President Barack Obama backs Democratic Senate Majority Leader Harry Reid's proposal, which would cut $2.2tn from deficits and raise the debt ceiling by $2.7tn, meaning the issue would not have to be revisited until after the 2012 elections. Late on Saturday, Mr Reid said he was postponing a planned procedural vote on his bill in the Senate - the latest stage in a series of Congressional stand-offs between the two parties. "There are negotiations going on at the White House to avert a catastrophic default on the nation's debt. There are many elements to be finalised and there is still a distance to go," he said. The vote, which had been expected at 0100 (0500 GMT) on Sunday, will now be held at 1300 (1700 GMT), he added. Mr Reid's deputy, Richard Durbin, said: "We're a long way from any kind of a negotiated agreement, but there is certainly a more positive feeling about reaching an agreement this evening than I've felt in a long time."