Minister-President of Lower Saxony, 2013–2025
Just weeks before the state election, opinion polls indicated that Weil, with the help of the Greens, would easily defeat incumbent Minister-President David McAllister. After McAllister's Christian-liberal coalition had been considered to be the winner until late in the night, Weil's red-green coalition eventually won the election by a wafer-thin majority, resulting in a narrow majority of just one vote in the state parliament. At the time, his victory constituted the twelfth consecutive setback in a state vote for Chancellor Angela Merkel’s CDU party and therefore was widely interpreted as indicative for the national elections later that year. Early on in his tenure, Weil emphasized consolidating Lower Saxony's finances.
As Lower Saxony has a 20 percent stake in Volkswagen (VW), Weil has been an ex-officio member of the company's supervisory board since February 2013. Within the supervisory board, he serves on the mediation and the nomination committees. Only a few months after Weil took office, Germany won a decisive victory over the European Commission in its bid to preserve state influence at VW, when the European Court of Justice rejected an attempt by the commission to abolish a state veto over key decisions such as factory closures, mergers and acquisitions.
In August 2017, Weil called for parliament to be dissolved a few months early and new elections to be held (elections had been planned for 2018), after one deputy, Elke Twesten, who had not been nominated for reelection by the Green Party, had quit her party and joined the CDU in the opposition, costing his coalition government its one-seat parliamentary majority. This had endangered Weil's position because it hypothetically would have enabled the CDU to elect their leader Bernd Althusmann as Minister President by a motion of no confidence.
Prior to the election, the SPD and its coalition had been in very low approval and poll ratings, but following this event the party won the election by a wide margin over the CDU, strongly improving their own result and winning many usual Greens voters for their best result since Gerhard Schröder in 1998. Nonetheless, the red-green coalition lost its majority by two seats due to the weakened Greens, even though the two parties came much nearer to a majority than deemed possible in the latest polls. Despite the rough election campaign between SPD and CDU and heavy accusations over the party affiliation change as a manipulative move to bypass voters and shift the parliamentary majority, Weil succeeded in negotiating and forming a grand coalition with the CDU and Althusmann after the election. In November 2017, he was again elected Minister President with the votes of SPD and CDU.
In 2024, in response to the threat of mass layoffs at Volkswagen, Weil wanted to restore government subsidies for the purchase of electric cars.
