BERLIN/WASHINGTON (Reuters) - Last month, in a phone conversation between Donald Trump and Angela Merkel, the U.S. president shared his views on Turkish leader Tayyip Erdogan.
"He's a great guy", Trump told the German chancellor, according to sources familiar with the exchange.
Merkel listened politely before pointing out that Erdogan had been lobbing vitriol at Germany and its European allies for weeks, denouncing them as the descendents of Nazis.
Trump was surprised, the sources said. He appeared unaware that Ankara and Berlin were in the midst of a fierce diplomatic row over whether Turkish ministers should be allowed to campaign in Germany for a referendum on boosting Erdogan's powers.
The White House did not respond to a request for comment. The German government declined comment, citing the confidential nature of the call.
The exchange, weeks after Merkel paid her first visit to Trump in Washington, underscored the challenge the German leader faces as she tries to forge a relationship with a president that half a dozen European officials who spoke to Reuters described as erratic, ill prepared and prone to rhetorical excess.
Six months after Trump's election and a little more than a week before he makes his first trip to Europe as president, officials in Berlin and other European capitals are still unsure about where the Trump administration stands on many of the big issues that concern them.
Coupled with this confusion is relief that he has not turned U.S. foreign policy on its head, as some feared, during his first months in office.
Trump is no longer calling NATO obsolete. And he has kept Russia's Vladimir Putin at arm's length. Apart from his suggestion last month that an attack on policemen in Paris would help far-right leader Marine Le Pen in the French election, Trump has not intervened in European politics or sought to undermine the European Union.
His controversial National Security Adviser Mike Flynn has been fired, replaced by H.R. McMaster, who is seen as a smart, steady hand. And the influence of Steve Bannon, the White House adviser Europeans fear most, may be on the wane.
"We feel there is now a productive working relationship," said Peter Wittig, the German ambassador to Washington.
But beneath the veneer are lingering questions about the president's character and his policies on a range of issues.
German officials remain worried about a shift to protectionism under Trump, despite his less confrontational rhetoric towards China and his decision to drop controversial plans for a border adjustment tax.
Several European diplomats expressed concern about what they view as the lack of a coherent U.S. strategy on Syria.
Some of them said the abrupt firing of FBI director James Comey showed Trump was capable of taking rash decisions on issues of major importance. Reports that he revealed highly classified information to Russia's foreign minister at a meeting in the Oval Office last week seem likely to aggravate the level of distrust in European capitals.
"The doubts about the professionalism of Trump's team, at least in foreign and security policy, have receded," one veteran German diplomat said. "But the doubts about Trump himself, his character, maturity and trustworthiness, have only grown."
A second German official said: "You shouldn't underestimate the influence of Trump on the Trump administration."
Few foreign leaders have as much riding on the relationship as Merkel.
Germany relies heavily on the United States for its security. And a tit-for-tat protectionist spiral could threaten its export-reliant economy.
In July, just two months before Germany holds an election, Merkel will host a tricky G20 summit in Hamburg, where Trump is expected to meet Putin for the first time. Turkish President Erdogan and China's Xi Jinping will also be there.
Merkel has been sparring with Putin and Erdogan for over a decade and worked with two U.S. presidents before Trump.
She formed a close relationship with George W. Bush in his Europe-friendly second term.
And although she got off to a tricky start with Barack Obama after denying him a chance to speak at the Brandenburg Gate during his 2008 campaign, the two ended up forming a close bond. Before travelling to Brussels to meet Trump on May 25, she will appear with Obama at the landmark in central Berlin.
Trump, her aides acknowledge, presents a unique challenge because of his unpredictability and ambivalent attitude towards Europe. He is deeply unpopular in Germany, making it politically awkward for her to get too close in an election year.
Nevertheless, there is satisfaction in Berlin that Merkel and Trump have gotten off to a relatively smooth start, after he accused her of "ruining" Germany with her open-door refugee policies and she responded to his victory by signalling she would only cooperate with him on the basis of common values.
The two leaders have spoken four times on the phone since her visit in mid-March. Both sides have played down the incident that dominated coverage of that visit: Trump's failure to shake Merkel's hand in the Oval Office.
Last month, Trump, the brash former real estate mogul from New York, told the Associated Press that he had "unbelievable chemistry" with Merkel, the reserved former physicist from communist East Germany.
German officials speak of a systematic effort by the chancellor to minimize tensions with Trump, pointing to the invitation she extended to his daughter Ivanka to attend a G20 women's summit in Berlin in April.
They note that Trump has not pulled out of the Paris climate deal, NAFTA or the nuclear deal between western powers and Iran, as he had threatened during his campaign for the presidency.
Trump has said he will not make a decision on the climate deal until after a G7 summit in late May, where Merkel and other European leaders are expected to lobby him hard to stay in.
"There are signs that this administration is capable of being influenced," said a senior French official. "You can talk to the people around Trump and give input. They are perhaps more malleable and open to outside views than many people thought."
During Merkel's visit in March, she spent a long time explaining to Trump and his team how the European Union worked, according to participants.
By the end of four hours of meetings - including a half hour one-on-one between the two leaders, a meeting with business executives, and a lunch - Trump had dropped his push for a bilateral trade deal with Germany and accepted that only an agreement with the EU was possible.
Although German officials acknowledge that the prospect of reviving TTIP - the transatlantic trade deal Europe tried to clinch with Obama - seems remote, they were pleased that Trump seemed open to the idea of negotiating with the EU.
They were also reassured that Trump proved to be a good listener. At the end of the two hour lunch, when aides to the president reminded him it was time to head off to his Mar-a-Lago resort in Florida for the weekend, he demurred, saying the discussion was going well and his departure would have to wait.
Officials in the German chancellery were pleasantly surprised when, 10 days after the visit, Trump called Merkel to congratulate her on a surprise win for her party in the tiny state of Saarland - even if he used the call, one source said, to harp about "fake polls".
The White House did not respond to a request for comment. The German government declined comment.
Over the past months, German officials have made a concerted effort to reach out to a wide range of officials in Washington, including people in the White House and Congress.
German Finance Minister Wolfgang Schaeuble met with Trump's economic adviser Gary Cohn during the spring meetings of the IMF and World Bank last month. His deputy Jens Spahn visited the White House, seeing Bannon and Trump's son-in-law Jared Kushner.
This outreach is especially important, German officials say, because top policy positions in the State Department remain unfilled more than three months since Trump took office.
But it is also a form of hedging. No one knows for sure who Trump is listening to today and whether that might change tomorrow.
"You simply can't afford to put all your eggs in one basket with this administration," said Robin Niblett, director of the London-based think tank Chatham House.
"Trump is on one day and off the other. One day you have a deal and the next day you don't. You have to hedge. And you have to cover yourself at home because he can dump you in it at any moment."
Additional reporting by Steve Holland in Washington; Editing by Anna Willard