In the federal elections of 2009, Westerwelle committed his party to a coalition with Merkel's CDU/CSU, ruling out a coalition with Social Democrats and Greens, and led his party to unprecedented 14.6% share of the vote.
In accordance with earlier announcements, he formed a coalition government with CDU/CSU.

On 28 October, Westerwelle was sworn in as Foreign Minister and Vice-Chancellor, becoming the head of the Foreign Office.
His deputies at the Foreign Office were his close political ally Cornelia Pieper and foreign policy expert Werner Hoyer as Ministers of State.
Hoyer had previously held the same office in the Cabinet Kohl V. In a much-discussed move, Westerwelle travelled to Poland, the Netherlands and Belgium before visiting France.

On 19 November 2009, Westerwelle joined around 800 dignitaries from around the world – including US Secretary of State Hillary Clinton, French Foreign Minister Bernard Kouchner and British Foreign Secretary David Miliband – to witness Afghan president Hamid Karzai’s swearing in for a second term in office.
In the federal elections of 2009, Westerwelle committed his party to a coalition with Merkel's CDU/CSU, ruling out a coalition with Social Democrats and Greens, and led his party to unprecedented 14.6% share of the vote. In accordance with earlier announcements, he formed a coalition government with CDU/CSU.
On 28 October, Westerwelle was sworn in as Foreign Minister and Vice-Chancellor, becoming the head of the Foreign Office. His deputies at the Foreign Office were his close political ally Cornelia Pieper and foreign policy expert Werner Hoyer as Ministers of State. Hoyer had previously held the same office in the Cabinet Kohl V. In a much-discussed move, Westerwelle travelled to Poland, the Netherlands and Belgium before visiting France.
On 19 November 2009, Westerwelle joined around 800 dignitaries from around the world – including US Secretary of State Hillary Clinton, French Foreign Minister Bernard Kouchner and British Foreign Secretary David Miliband – to witness Afghan president Hamid Karzai’s swearing in for a second term in office.
Guido Westerwelle