German Chancellor Angela Merkel and US President Barack Obama say they favour sealing a US-European free trade agreement as it will fuel growth on both sides of the Atlantic.
Merkel is expected to discuss the Trans-Atlantic Trade and Investment Partnership (TTIP) with Obama when he visits a trade show in Hanover on Sunday and Monday (local time). Support for TTIP has plunged in both their countries, however.
Tens of thousands of protesters marched in Hanover on Saturday to express their opposition to the deal.
Police said 35,000 people took part in the demonstration, while organisers said more than double that number had attended.
Protesters held placards reading "Stop TTIP" and "For a fair world trade."
"The Trans-Atlantic Trade and Investment Partnership is one of the best ways to promote growth and create jobs," Obama told the mass-selling newspaper Bild in an interview.
Merkel said in her weekly podcast that wrapping up a deal would be a "win-win situation," adding that "it is good for us as we will be able to appraise our competitors."
The United States is Germany's biggest trading partner.
Advocates of the trade deal say it would unleash further growth while critics warn it could undermine consumer rights and environmental protection.
Speaking separately in London on Saturday, Obama said the trade deal had run up against "parochial interests" of individual countries but would create millions of jobs and billions of dollars of benefits.