Ahead of next year's expected spending review (which would cover spending from 2015-2017), the Guardian's Patrick Wintour reports  that the Tories are unsure whether they will be able to repeat their 2010 pledge to ring-fence spending on health and international development.
Given the deteriorating fiscal situation, this is no surprise. When George Osborne delivered his first Budget in June 2010, the newly-established Office for the Budget Responsibility forecast  that the deficit would fall from £154.7bn (11%) in 2010 to £37bn (2.1%) in 2015. But the failure of Osborne's strategy to deliver growth (indeed, its success in delivering recession) means that, according to the latest independent forecasts , it will now stand at £96.1bn (5.8%).
In response, the Chancellor has already been forced to extend his austerity programme by two years to 2017 (going further, David Cameron has suggested  he may need an extra five) and has declared his intention to seek another £10bn of welfare cuts  (the reason he tried - and failed - to remove Iain Duncan Smith, who is opposed to further cuts , from his post in this week's reshuffle). With the fiscal situation likely to worsen further as growth remains anaemic or non-existent (the OECD today predicted that the UK economy would shrink by 0.7% this year, a worse peformance than any G7 country except Italy), Osborne is on the hunt for further savings.
Few Tory MPs would weep at the demise of the NHS/overseas aid ring-fence (many were outraged that defence spending was cut by 7.5%, while overseas aid received a 35% real-terms increase) but such a decision would inflict further damage on Cameron's brand. Against this, the Tories believe that a 2013 spending review would cause trouble for Labour by forcing it to come clean about where it would cut. As Treasury select committee chairman Andrew Tyries has said: "Labour would have to respond. Having the coalition parties committed to the same spending path halfway into the next Parliament makes it very difficult for Labour at the election."
The biggest question facing Balls and Miliband remains whether to accept the Tories' spending plans, as Labour did in 1997, or offer a distinct alternative.