the Progressive Alliance in 2013 by canceling the SPD payment of its £100,000 yearly membership fee to the Socialist International in January 2012. Gabriel had been critical of the Socialist International's admittance and continuing inclusion of undemocratic "despotic" political movements into the organization. For the 2013 federal election, Gabriel was considered a possible candidate to challenge incumbent Chancellor Angela Merkel but deemed too “unpopular and undisciplined” at the time. As a consequence, he and the other members of the party's leadership agreed to nominate Peer Steinbrück after Frank-Walter Steinmeier, the party's parliamentary leader, withdrew from the contest. During the election campaign, Gabriel became the first SPD leader to address a party convention of Alliance '90/The Greens; in his speech, he called for a red–green alliance to defeat Merkel in the elections. Vice-Chancellor and Federal Minister, 2013–2018 In 2013, Gabriel turned the Social Democrats’ third successive defeat to Angela Merkel in the federal election into a share of government, after successfully navigating the three-month process of coalition negotiations and a ballot of about 475,000 party members, who endorsed the accord. At the time, he was widely considered to have negotiated skillfully, particularly considering the relative weakness of his party, which had received just over 25 percent of the vote in the elections, against more than 41 percent for Merkel's conservative bloc. At an SPD convention shortly after the elections, however, Gabriel and the other members of the party's leadership were punished by delegates who re-elected them to their posts with reduced majorities; he received 83.6 percent of members’ ballots after 91.6 percent at the previous vote in 2011. Gabriel, who serves as vice-chancellor in the third Merkel cabinet, took on responsibility for Germany's energy overhaul as part of a newly configured Economy Ministry. Since late 2016, he has been a member of the German government's cabinet committee on Brexit at which ministers discuss organizational and structural issues related to the United Kingdom's departure from the European Union. Speculation about Gabriel's future as leader of the SPD has been brewing since he registered just 74 percent in a party delegates' vote of confidence in December 2015 – the lowest for an SPD leader in 20 years. On 24 January 2017 Gabriel announced that we will not run as candidate for chancellor in 2017; instead, he proposed that Martin Schulz become candidate and replace him as party chairman. Gabriel also announced that he