Over the last 15 years, Europeans have had rather disappointing experiences with American presidents. That's just as true for the relationship with Republican George W. Bush as it is for the one with Democrat Barack Obama. The Bush years were dominated by disagreements over the Iraq war and America's war on terror. Bush divided Europeans into those who were with him, and those who were against him. Europe also found itself deeply divided over his course.

When Obama took office in January, 2009, many Europeans were hoping for the start of a new era in transatlantic relations. When his new Secretary of State Hillary Clinton first came to Brussels, she received an enthusiastic welcome. The Ice Age appeared to be over. But it was hard to really speak of a new closeness between the US and Europe. Obama wasn't all that interested in Europe, and it showed. He, instead, became famous for his "pivot" toward Asia.

Focus on Europe

Many on either side of the Atlantic are once again hoping to revive the transatlantic partnership. "Europe should occupy the top spot on the list of priorities for the next president, because it's about the most important strategic alliance the United States has," said Erica Chenoweth, an expert on international security policy at the University of Denver.

"The next president needs to turn toward Europe in a way we haven't seen since the 1990s."

For James Jay Carafano, national security expert at the conservative Heritage Foundation in Washington, it's important that the next occupant of the White House concern his or herself with peace and security in Europe. He sees Russia as a threat to both. "The most important question for American security policy is going to be Russian foreign policy in Europe," Carafano said. The US needs to do more for a "unified NATO that really concentrates on its core mission, namely defending the transatlantic community," he added.

Constraints on Clinton

No matter who wins the election, Europeans need to get ready for change, said Yanis Emmanouilidis of the Brussels-based European Policy Center. In the event of a Trump victory, "a lot will change, because his positions are radically different from those of past presidents, or past administrations," Emmanouilidis said. But even in the case of a President Clinton, there will be change. "She will be governing a deeply divided country," he said, meaning that she will face pressures that will "have an effect on her foreign policy decisions."

Ronald Freudenstein of the Brussels-based Martens Center has also warned against the "illusion that, under Hillary, everything will be much the same as it was before," even if it's clear that the bigger change would come from a Trump presidency. "The anger against the establishment that both Trump and Bernie Sanders have embodied is a factor with which Hillary Clinton will have to come to terms. That will affect everything from the economy and trade to foreign policy. Even if she has much more sensible ideas in all these areas than Trump, she will have to take into account the frustrations of many lower- and middle-class Americans," he said.

TTIP? Maybe later

According to Emmanoulidis, Clinton stands for a certain continuity on matters such as Russia or Syria, although she would demand "more responsibility" from Europeans generally in the areas of security, defense and foreign policy. If Trump wins, however, more radical change can be expected, he said. "American will be more isolated, and it will take a tougher stance," said Emmanoulidis. Ronald Freudenstein agreed, adding: "Under Trump, US foreign policy would become unpredictable."

With the recently signed free trade agreement with Canada, it became clear that many of the problems are on the European side. That would likely also be the same with TTIP, the planned trade agreement with the US. Yanis Emmanouilidis believes that under President Clinton, the Americans would be interested in pursuing TTIP, making an agreement possible after a certain timeframe - "maybe a year."

Limited choice of partners

Both experts see parallels between Trump and the euroskeptic, authoritarian, anti-foreigner movements in Europe. Roland Freudenstein sums them up as "anger against the elites, fear of globalization, and the re-discovery of identity politics." But he predicts that "the pendulum will eventually swing to the other side when it becomes clear that all these populist movements produce nothing but chaos."

But after all these years of chilly relations, will there really be a renaissance in the transatlantic partnership?

Both experts say that's hard for them to imagine under a Trump presidency. And if Hillary Clinton wins, it still doesn't mean there'll be a return to the close relations seen during her husband's tenure in the White House.

But Yanis Emmanouilis believes the chances are better with Clinton. "Hillary Clinton knows, and people in Europe know, too, that in times of such great uncertainty, we need each other. In the end, there aren't that many strong partners that you can have on your side."