The Guardian | Julian Borger and Patrick Wintour : President unlikely to certify pact this week, triggering complex battle in Congress and Europe over ultimate fate of agreement

If Donald Trump decides this week to withdraw his endorsement of the 2015 Iran nuclear deal, its fate and the potential for a major conflict will be determined by a complex battle in Congress.

No one is able to predict whether that struggle will lead to a reimposition of US sanctions, the collapse of the agreement and the rapid scaling-up of Iran’s nuclear programme. It could result in a compromise that leaves the deal alive but opens the way for a more combative policy towards Tehran on other fronts.

“We are on a tightrope. We don’t know what will happen,” a western diplomat said.

The congressional contest will pit most Republicans against almost all Democrats, hawks against doves, and will be played out under rules drawn up for a completely different set of circumstances.

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