U.S. President Barack Obama is in his adopted hometown of Chicago for a gala celebration and fundraiser on the eve of his 50th birthday.

Attendees Wednesday evening paid up to $35,800 for a ticket — money that will go towards the president's re-election campaign and the Democratic National Committee. The festivities include a concert featuring Chicago musical stars Herbie Hancock and OK Go, and, for the biggest donors, dinner with Mr. Obama.

The White House says the president will be back at work in Washington on his birthday Thursday morning, but says the celebration will continue later in the day when the Obamas host a private party in the Rose Garden.

Earlier Wednesday, Mr. Obama received a birthday telephone call from Russian President Dmitry Medvedev. White House spokesman Jay Carney said the two leaders discussed Russia's 18-year quest to join the World Trade Organization.

Carney said the two leaders agreed that “significant progress” had been made, but that Mr. Obama urged Russia to negotiate with WTO members to resolve the remaining issues.

One outstanding issue centers on objections by foreign automakers that they commit to major production in Russia if they want lower import fees for car parts.

President Obama also spoke with Russian reporters, telling them that the new nuclear disarmament treaty between Russia and the United States is an example of “tremendous progress” made in bilateral ties. Mr. Obama noted that when he was born during the Cold War, no one would have imagined that Washington and Moscow would be partners on the international stage.

Russia has released a postage stamp, matching envelope, and postmark in honor of Mr. Obama's birthday.