German Vice Chancellor Sigmar Gabriel said Brexit is taking “far too long” and maintaining the U.K.’s ties to the European Union won’t be easy.

Gabriel signaled concern that extended uncertainty implied by U.K. Prime Minister Theresa May’s timeline for starting Britain’s exit from the EU by the end of March might cause economic damage, though “we’re not experiencing a strong impact” for now.

“The general insecurity is the biggest problem,” Gabriel, who also is economy minister in Chancellor Angela Merkel’s government, told foreign reporters in Berlin on Thursday. “In our estimation, the process is taking far too long.”

U.K. lawmakers late Wednesday backed May’s target date for triggering Brexit after she promised to give Parliament the chance to scrutinize her plan first. The prime minister has been unwilling to give details of her negotiating strategy, saying it would give an advantage to Brussels.

Germany and its EU allies should do “everything possible” to keep bridges between the bloc and the U.K. intact, Gabriel said. “That won’t be easy,” he said.

The U.K. could seek to model its new relationship on trade rules used by Switzerland or Norway, Brexit Secretary David Davis told Parliament on Wednesday. The government is considering at least four different options for Britain’s future relationship with the customs union, which imposes common tariffs on external countries while allowing EU members tariff-free trade with each other, he said.