Almost six years after Washington's war on Iraq damaged ties with Brussels and divided Europe, EU leaders invested a lot of hope that Obama will re-unite with them to confront global challenges when he starts his first whole day in office on Wednesday, Jan. 21.

"Acting together represents one of the best ways to respond to the needs and hopes of peoples on both sides of the Atlantic," the EU's Czech presidency said in a statement on Tuesday.

Iraq and Afghanistan are expected to dominate Obama's foreign policy agenda, but he has also said he will take an active role to try to resolve the Israeli-Palestinian conflict.

EU, US to face global challenges together

EU foreign policy chief Javier Solana said in an article in the Financial Times the start of the Obama administration was an opportunity for the US and EU to confirm their commitment to multilateral diplomacy.

Offering "five lessons in global diplomacy," Solana outlined the importance of political rather than military force, of keeping domestic politics in mind during international interventions and of accepting that "no single country, even the US, can solve problems on its own."

The EU looks forward "to cooperating closely with the new US administration for the steady advancement of the trans-Atlantic partnership and for its continuous adaptation to the tremendous challenges posed by a changing world."

European Commission President Jose Manuel Barroso said the EU and United States would have to work together to face the international challenges posed by a globalized world.

"We are living through challenging times," Barroso said in a statement. "And the challenges we face have no respect for national frontiers."

He said Washington and European Union members should work closely together to respond to the ongoing economic crisis, peace and security issues, including in the Middle East, and in the fight against climate change.

"I personally believe that the election of President Obama was a defining, turning point for America," Barroso said. "It may now also be an important turning point for the rest of the world."