New Secretary of State John Kerry reported for duty Monday, acknowledging that as Hillary Rodham Clinton’s successor he has “big heels to fill” and promising to protect U.S. foreign service workers from terrorist attacks overseas.

On his first day at the office in his new job, the former senator and 2004 Democratic presidential candidate was greeted with loud cheers by employees of the State Department and the U.S. Agency for International Development.

As the first man in the post in eight years, Kerry referred to his two most recent predecessors, Clinton and Condoleezza Rice, by asking in jest: “Can a man actually run the State Department?”

“I don’t know,” he answered. “As the saying goes, I have big heels to fill.”

Kerry told his new agency’s employees that he and President Barack Obama needed their help to make America safer and the world more prosperous and peaceful.