U.S. President Donald Trump | Andrew Harrer/Pool photo via Getty Images Big EU powers fail to convince on new Iran sanctions France, Germany and the UK hoped to use new penalties to persuade Trump to preserve nuclear accord.

The EU powers that helped broker the Iran nuclear accord have failed to win support for new sanctions that would punish Tehran for its destabilizing actions in Syria.

The effort was aimed partly at blunting efforts by U.S. President Donald Trump to dismantle the nuclear deal, and the failure to impose new penalties increases the likelihood that Trump will move to dismantle the accord next month.

Diplomats from the so-called E3 – France, Germany and the U.K. — have been lobbying for weeks for the new sanctions, which can only be approved unanimously, but have run into staunch resistance from several countries including Austria, Cyprus, Greece, Italy, Spain and Sweden.

Trump has voiced angry criticism of the 2015 Iran nuclear accord, formally known as the Joint Comprehensive Plan of Action, and in January he set a May 12 deadline for European allies to address his complaints, or said he would allow the automatic re-triggering of U.S. sanctions, which have been suspended under the terms of the accord.

The EU powers, by contrast, have repeatedly voiced strong support for the deal, which they say has subjected Iran's civilian nuclear program to the most intensive external monitoring ever seen, and halted Tehran's efforts to build an atomic weapon.

Diplomats, speaking in briefings ahead of a meeting on Monday of EU foreign ministers, said the effort to build consensus for new sanctions would continue and that there was still a chance of agreement before May 12.

Monday's meeting of the Foreign Affairs Council is the last formal gathering where ministers can approve new sanctions in person. To do so before Trump's deadline, they would have to act using the Council's "written procedure" — an emergency process.

Officials said that in a series of heated discussions in recent weeks, Paris, Berlin and London put forward a list of 15 entities and people they want to sanction, which are linked to Iran's military intervention in Syria and its support for Syrian President Bashar al-Assad.

French President Emmanuel Macron and German Chancellor Angela Merkel are scheduled to visit Washington for separate meetings with Trump later this month. A vote by foreign ministers on new sanctions would have given them a powerful card to play at the White House.

Prospects of maintaining support for the nuclear accord in Washington have dimmed since the ouster of Secretary of State Rex Tillerson.

EU opponents of the E3 proposal say there is little reason to believe the new sanctions would be enough to assuage Trump, while the new punitive measures could undermine Tehran's commitment to the nuclear deal. The opponents also note that two other architects of the nuclear accord, China and Russia, continue to support it — leaving Trump isolated in his opposition.