After months of positive build-up to the Vienna talks on Iran’s nuclear programme, world leaders once again emerged with a deal looking a long way off.

Iran and the P5+1 group of countries have agreed to put together a political framework for the agreement by 1 March and hammer out a final deal by 1 July.

With distances remaining between the two sides’ negotiating positions and hardline domestic political influences threatening to scupper any kind of compromise, the negotiators more than ever have their work cut out.

In principle, both sides agree on what a deal would look like: Iran must roll back its uranium enrichment programme to the extent that it is unable to make a nuclear weapon, in exchange for the lifting of international economic sanctions.

Although there are major sticking points on how quickly the US and its allies would provide sanctions relief and the amount of time the agreement would remain in place, negotiators have crucially failed to agree on what a peaceful nuclear programme would look like.

Iran currently has 19,000 centrifuges installed at its enrichment plants in Fordow and Natanz, and does not appear to be willing to reduce this volume. The P5+1 group insists that under an agreement, Tehran would have to reduce this number to 4,500, and demand that the remainder are neutralised, with parts given to the International Atomic Energy Agency.

Iran’s President Hassan Rouhani is under pressure from the country’s Supreme Leader Ali Khamenei not to give too many concessions to the programme and it is unclear whether he will be given enough room to manoeuvre to reach a compromise with the US.

On top of this, there is an underlying sense of distrust between Iran and the US. Hardliners in Washington accuse Tehran of pursuing nuclear developments in secret and will seek to derail any agreement that gives the Islamic Republic too much freedom. The Republican victory in the US mid-term elections will bring even more dissenting voices into Congress.

Although negotiators on both sides say progress is being made to narrow the gaps, reaching a consensus by March will be, if not impossible, a very difficult task.