It’s hard to overstate the importance of the Iran nuclear deal. That much was evident on Tuesday when oil prices hit a fresh high above $75 a barrel after US President Donald Trump called the deal “insane”.

That his French counterpart Emmanuel Macron kept the issue at the top of the agenda during his state visit to Washington shows too just how much Europe wants to keep the deal sweet in some shape or form.

Such is the importance of the Iran agreement to its European signatories, that it’s even been suggested Britain and France’s willingness to chum up alongside the US over the recent airstrikes on Syria, was perhaps influenced by the need to curry favour with Mr Trump in the hope he would think again about not scrapping the deal.

READ MORE: Britain ready to work with allies on new Iran deal

Time is running out after all, with a May 12 deadline looming for the US president to decide whether to pull the US out of an accord the official name of which is the Joint Comprehensive Plan of Action (JCPOA).

Mr Trump of course has long telegraphed his desire to undo the nuclear deal, insisting to European signatories that they have to “fix” it or Washington will withdraw from the pact and sanctions on Iran will be reinstated.

His terms are pretty demanding and include an end to clauses in the deal that would allow Iran to enrich uranium beyond the amount usually needed for commercial power production. Mr Trump also wants a ban on ballistic missile testing and unlimited access for atomic energy inspectors to any military site.

Over the last few days President Macron, who has been at the forefront of European efforts to preserve the deal while responding to Mr Trump’s concerns, said the two leaders had floated “new” solutions during bilateral talks at the White House.

Many though remain very sceptical that MrMacron can pull such a rabbit from the diplomatic hat, so entrenched has the Trump administration been for some time now in its efforts to undermine the deal.

READ MORE: Britain ready to work with allies on new Iran deal

Apart from its European signatories, there is no shortage of those who oppose scrapping the deal and who flag up the real dangers of doing so.

Late last year eighty of the world’s leading nuclear non-proliferation experts issued a joint statement, arguing that the nuclear deal “has proven to be an effective and verifiable arrangement that is a net plus for international nuclear non-proliferation efforts.”

More recently a bipartisan group of more than 100 US national security experts, including nearly 50 retired military officers and more than 30 former ambassadors, also urged Mr Trump to stay the course.

The group’s conclusion in its own joint statement was that not only would ditching the deal “serve no national security purpose,” but it would also weaken Washington’s hand in dealing with other nations developing nuclear weapons capabilities like North Korea, and seriously erode the “reliability of America's word and influence as a world leader.”

So why then despite the glimmer of hope over the last few days following Mr Macron’s visit is Mr Trump seemingly so hell-bent on seeing the deal unravel?

READ MORE: Britain ready to work with allies on new Iran deal

Well, to begin with, there is the Obama factor with Mr Trump long resenting the fact that his predecessor Barack Obama negotiated the 2015 agreement.

Until now Mr Trump - albeit reluctantly - has minded to keep the US onside in the deal, influenced by pressure and advice from close advisers like former secretary of state Rex Tillerson.

But all that changed when Mr Trump’s top team saw a spate of foreign policy uber-hawks move into key positions. Among them is Mike Pompeo who succeeded Mr Tillerson and, most notably, former US ambassador to the UN John Bolton, Trump’s new national security adviser.

Both have never pulled their punches when it comes to Iran, with some suggesting that Mr Bolton would settle for little less than regime change in the country even if it meant the catastrophic possibility of going to war with Tehran regime.

Let’s not forget too the influence of Israel’s lobbyists on the US congressional body politic. Nothing would suit them and Israeli Prime Minister Benjamin Netanyahu more than seeing the Iran deal coming unstuck and Tehran getting a bloody nose if needs be in the process. They too have made their presence felt on Mr Trump’s thinking to date.

Given all this the signs are not good, and Mr Macron’s efforts might yet all still prove in vain. According to the influential political risk consultancy Eurasia Group, the odds of the nuclear deal’s survival after Mr Trump’s remarks yesterday were reduced from 55 per cent to 35 per cent.

The group also says it now looks unlikely that the deal would survive his first term in office. It warned too that Tehran would likely react with “rhetorical fury” to the scrapping of the deal and could “likely lash out” in the Middle East. Think tumbling markets and rising terrorism and the potential picture is not a pretty one.

Few doubt that should the deal collapse and the systems in place tomonitor Iran’s nuclear activity undermined as a result, then almost certainly it would make proliferation more likely.

READ MORE: Britain ready to work with allies on new Iran deal

If the full impact of American sanctions including penalties on importing Iranian crude oil, snap back into place, Iran’s economic situation would almost certainly deteriorate. The early warning signs are already there, with the Iranian rial plunging against the US dollar in recent months.

Let’s remember that Iran has the fourth largest crude oil reserves in the world and claims nearly one-fifth of the planet’s natural gas. New sanctions on Iranian oil exports would not only put a dent in global supply but cause prices to spike even higher than the $75 a barrel seen over the past few days.

All of which should focus the minds of those who pay for petrol but think that such distant affairs rarely impact right here on our doorstep.

There is the chance of course that all this doesn’t come to pass and that Mr Macron was able to convince Mr Trump.

Should his reasoning though have fallen on deaf ears in the White House, then the Iran nuclear deal will be on the path to collapse. Equally worrying is that Mr Trump appears to have no realistic plan for what to do next when the inevitable regional and global fallout follows.