German Chancellor Angela Merkel's meeting with President Donald Trump could cause a backlash for her if things go south, global policy expert Joerg Forbrig told CNBC on Friday.



"I think she's taken this visit and the preparation, especially to this visit, extremely seriously," Forbrig, a senior transatlantic fellow for Central and Eastern Europe, and director of the Fund for Belarus Democracy, said in an interview with "Squawk Box."

"We know, for instance, she's read articles on Donald Trump from a 1990 edition of Playboy magazine. That's how deeply she's delved in order to avoid exactly the sort of things going wrong that we have seen going wrong with a couple of leaders that have already come to Washington to see Donald Trump," he said, speaking from Germany.

On Friday, Merkel, whose country has Europe's largest economy, will meet with Trump at the White House to reportedly discuss funding for NATO and relations with Russia in their first meeting since Trump took office.

Forbrig, of the German Marshall Fund of the U.S., said the two leaders' long-distance relationship hasn't been easy. They have had a tense history and clashed publicly. Trump for instance has criticized Merkel for her handling of the Syrian refugee crisis.

Forbrig said some of the differences between Merkel and Trump will need to be smoothed over as the chancellor heads into a re-election campaign.

"President Trump is probably the least popular U.S. president in a very long time. If this meeting somehow doesn't succeed ... this would certainly be a liability politically for Angela Merkel here in Germany."

"I think she will have to get along with him," he said. "There's a whole set of issues of cooperation and a normal working relationship across the Atlantic. It is simply indispensable."

— Reuters contributed to this report.