The Washington Post | Karen DeYoung: When French President Emmanuel Macron called last week for new international sanctions and �surveillance� over Iran�s ballistic missile program, there was one person in particular he hoped was listening.

France, Germany and Britain have been scrambling for months to convince President Trump that they want to join him in cracking down on bad Iranian behavior � missile tests, terrorism support and regional meddling. If they can sway him, they hope he will agree to preserve intact�the 2015 Iran nuclear agreement�he has argued is fatally flawed.

The administration, led by the State Department, has embarked on high-level talks with the Europeans to try to find a way to address Trump�s concerns before a May�12 deadline he has set for leaving the deal. Many involved in the effort believe success is both possible and desirable, and Secretary of State Rex Tillerson last week described discussions so far as �very fruitful.�

Trump has also tasked Congress with legislating changes in the agreement in the same time frame. He has demanded not only that non-nuclear issues be addressed but also that the deal itself be altered to eliminate sunset clauses for some of the restrictions it places on Iran, to harden the inspection rules and to limit development of long-range missiles the United States maintains could be used to deliver nuclear payloads.

The Obama-era deal came into being with few friends in Congress, and some Republican hawks have called for killing it outright. Until late last year, when the White House told the Europeans in no uncertain terms to stop interfering in U.S. internal affairs, the Europeans had directed much of their pro-agreement sales pitch to lawmakers.

Now, Congress is in limbo on the issue, waiting to see whether the administration can strike a deal with its partners in Europe.

�We�ve got to have the Europeans because of the Democrats,� Senate Foreign Relations Committee Chairman Bob Corker (R-Tenn.) said last week. �They�re not going to vote for something the Europeans don�t support. .?.?. We�re in hold mode until [the administration] has a breakthrough with our European friends.�

Sen. Benjamin L. Cardin (Md.), the ranking Democrat on the committee until earlier this month, agreed that �the game plan right now is to see where they can go with the Europeans.�

But no one knows whether the all-important audience of one even wants to retain an international accord he has called an �embarrassment� to the United States and has threatened to rip up since early in his presidential campaign. Even if negotiators can agree, several foreign and U.S. officials close to the talks said, there is no guarantee that an agreement will placate the mercurial chief executive.

�It seems to me some of this can be done,� Cardin said of the negotiations. But �I can�t speak for the president, and I�m not so sure the people around him can speak for the president.�

For the three leading European allies, outright U.S. withdrawal or insistence on a rewrite that they � let alone Iran and fellow signatories Russia and China � have said they will never accept, could spark the most serious international rift with the administration to date.

�This will not blow over,� said one official, among a half-dozen who discussed the issue on the condition of anonymity, most out of fear of provoking a Trumpian tweetstorm or worse.

In a random Twitter post�among many attacking the ongoing Russia investigation last weekend, Trump excoriated the FBI, Congress and the Justice Department for not investigating the return of $1.7�billion in frozen Iranian funds to Tehran as part of the nuclear deal.

Overall, Trump said when he set the May deadline last month, the deal �gave Iran far too much in exchange for far too little.� His objections, loudly seconded by Israel and other antagonists in the neighborhood such as Saudi Arabia, concern what is in the agreement as well as what was left out.

As they hammered out the Iran deal over several years, negotiators intentionally bypassed concerns such as ballistic missiles, terrorism and Iranian expansionism in the Middle East � all of which are addressed in separate sanctions and United Nations resolutions.

The rationale, European and Obama administration officials said at the time, was that Iran�s development of a nuclear weapon was a far more immediate and dangerous threat, with a breakout window of mere months at the time. Ultimately, existing sanctions designed to prevent Iran from developing nuclear weapons were lifted � and frozen Iranian funds were released � in exchange for strict limits and intense international monitoring of a program Iran insisted was designed only for research and nuclear power production.

Since the agreement went into effect, the International Atomic Energy Agency has regularly certified�that Iran has abided by its terms.

�That�s part of the problem,� said a senior administration official involved in developing Trump�s Iran policy. �This was an agreement struck out of the context of the broader problem of Iran�s behavior.�

�The president laid out six major areas where he wanted the Europeans to work with the United States to put together a united front on demanding that the Iranians alter their behavior,� the official said, also including human rights violations, cyberthreats and the financial activities of the Iranian Revolutionary Guard Corps.

From the beginning of his administration, Trump has accused the Europeans of being soft on Iran and largely interested in making money there. National security adviser H.R. McMaster was said to have dismissed a position paper one of the allies delivered to the White House early last year as something that �the ayatollah� could have written.

Two statutory mandates have given Trump the opening to directly threaten the agreement. One, imposed by Congress when it allowed the agreement to move forward in 2015, requires the president to certify Iranian compliance every 90 days. After two rounds of certification, Trump said last October that he would issue no more certifications.

More ominous is that pre-deal sanctions related to Iran�s nuclear program, lifted when the agreement went into effect, must be waived by the president every 120 days.�Trump issued the waivers in mid-January�along with a warning that he was doing so �only in order to secure our European allies� agreement to fix the terrible flaws of the Iran nuclear deal.�

�This is the last chance,� he said. �No one should doubt my word.� May�12 is the next waiver deadline.

Each of the European allies has chosen a somewhat different response to Trump�s threats and demands. Macron, the French president, has tried to embrace his U.S. counterpart, hosting him for Bastille Day ��an occasion on which Trump so admired the military parade he now wants one at home�� coming down hard on Iranian non-nuclear behavior, and choosing not to confront Trump on false or uninformed statements about what the agreement says and whether Iran is complying with it.

Macron, whose foreign minister is to visit Tehran next month, has also indefinitely put off a planned trip there. He is to make a late-April state visit to the United States, the first for the Trump administration.

Germany has vacillated between thinly veiled public criticism, calls for European unity and doleful reflections on the state of affairs. At last week�s Munich Security Conference, German Defense Minister Ursula von der Leyen denounced Trump�s military-heavy approach to the world, which she said was being pursued at the expense of diplomacy and international aid. At the same event, German Foreign Minister Sigmar Gabriel remarked that �we no longer recognize our America.�

Britain, preoccupied with the economic and security problems of leaving the European Union, has echoed the concerns more forcefully expressed by the others and their eagerness to find a path to approval by Trump. British Prime Minister Theresa May said during a visit with German Chancellor Angela Merkel on Friday in Berlin that both remain �ready to take further appropriate measures� to address U.S. concerns about aspects of Iranian behavior.

Once the deal�s multiyear sunset provisions restricting Iran�s uranium enrichment levels and its use of centrifuges expire, they argue, Iran will be brought under international compacts with perpetual restrictions on weapons development and continued tight verification.

From their side of the negotiating table, they would like the White House and Congress to find a way to remove the regular Iran crisis triggers that are primed every 90 and 120 days.

But even if negotiations succeed, and even without the deadlines, they acknowledge, the U.S. president will retain the right to withdraw from the nuclear agreement any time he wants to do so.

Karoun Demirjian in Washington, Griff Witte in Berlin, William Booth in London and James McAuley in Paris contributed to this report.