WASHINGTON (AP) — German Chancellor Angela Merkel was making the case Tuesday for a global deal on climate change to a skeptical audience: members of Congress.

Merkel was addressing both chambers of Congress, a rare honor extended to America’s closest allies and not to a German chancellor since Konrad Adenauer in 1957. She was to meet with President Barack Obama before the speech.

It is an opportunity for Germany to make a case to the lawmakers whose support will be crucial if the United States is to sign on to a new global climate deal that European leaders and Obama are seeking.

Merkel’s address comes ahead of the 20th anniversary Nov. 9 of the fall of the Berlin Wall, and she also was expected to highlight the trans-Atlantic cooperation that brought it down. The theme of solidarity probably will touch on Germany’s commitment to Afghanistan, a delicate issue for Merkel. The United States has urged European countries to step up efforts in NATO’s operations, but the war is unpopular in Germany.

The speech comes less than a week after Merkel was sworn in for a second term. Her formation of a new center-right coalition has created some expectations in Washington that the coalition would make it easier for Merkel to support the United States on Afghanistan and other foreign policy issues, including reining in Iran’s nuclear program.