in 2007, Bartsch became federal managing officer of the new party. Bartsch managed The Left's 2009 federal election campaign. The party won 11.9% of votes nationwide and 76 seats in the Bundestag; he was re-elected at the top position of the party list in Mecklenburg-Vorpommern. In January 2010, after disputes within the party, Bartsch announced he would not seek re-election as federal managing officer at the party congress in May. Later in January, he became deputy chairman of the Left's Bundestag group. In this position, he focused on the national budget and finances. In January 2012, Der Spiegel reported that 27 of the Left's 76 members of the Bundestag were under surveillance by the Federal Office for the Protection of the Constitution, including Bartsch. The surveillance of Bundestag deputies, including many such as Bartsch who were not connected with groups classified as anti-constitutional, was criticised by the FDP, SPD, and Greens. The monitoring of Bundestag deputies without clear cause was ruled unconstitutional by the Federal Constitutional Court in 2013, and surveillance of The Left's deputies was discontinued. In late 2011, Bartsch declared his intention to run for party chairman at the 2012 party congress, even after incumbent Oskar Lafontaine announced his desire to seek re-election. Lafontaine withdrew before the congress, and Bartsch was defeated by Bernd Riexinger, an ally of Lafontaine from the party's left-wing. Bartsch won 251 votes (45%) to Riexinger's 297 (53%). Bartsch was elected co-leader of the Left's Bundestag group in 2015 alongside Sahra Wagenknecht, succeeding long-time leader Gregor Gysi. Bartsch won 91.6% of votes cast. As the Left was at the time the largest opposition party in the Bundestag, Bartsch became a prominent leader of the opposition for the remainder of the parliamentary term. Bartsch and fellow parliamentary leader Wagenknecht were the Left's lead candidates for the 2017 federal election. The party made small gains in the election, though they fell from third to fifth place with 9.2% of votes and 69 seats. Bartsch contested the Rostock – Landkreis Rostock II constituency and placed second behind the victorious CDU candidate, winning 24.8% of votes. Ahead of the 2021 federal election, Bartsch was once again chosen as one of The Left's two lead candidates alongside new party co-leader Janine Wissler. They were confirmed with 87% of votes by the party executive on 9 May. Political positions Bartsch is considered a prominent leader of the moderate, reformist wing