An economist by profession, Marian Lupu was promoted to public office for many years by former president Vladimir Voronin. From 1991 until 2005, he worked at the Ministry of Economy, climbing the ranks from specialist to deputy minister and later minister. In 2005, he became a member of Parliament after running on the list of the Party of Communists of the Republic of Moldova and was elected speaker of the Legislature.

In 2009, he broke away from Voronin’s influence and joined the Democrats’ camp, controlled by oligarch Vladimir Plahotniuc. At that time, Lupu was appointed president of the Democratic Party of Moldova, becoming a central figure in promoting Moldova’s European integration and one of the architects of the Alliance for European Integration (AIE) in 2009.

Between 2010 and 2012, he served as acting president, later continuing his work as a deputy.

In 2016, Lupu was the PDM’s candidate for the presidency. It was the first time in 20 years that the president was elected directly by the people and not by Parliament, as before. During the campaign, he announced his withdrawal and called on his supporters to vote for Maia Sandu, the candidate of the Action and Solidarity Party. She later claimed that his withdrawal was actually in favor of her rival, the socialist Igor Dodon, who won the election.

Subsequently, Lupu handed over the leadership of the Democratic Party to Vladimir Plahotniuc but remained vice president. He left the party in 2019 when he was appointed president of the Court of Accounts.

In 2020, an investigation by RISE Moldova revealed that an offshore company controlled by oligarch Vlad Plahotniuc had made two bank transfers totaling 19,000 euros to Maastricht University in Netherlands to cover the tuition fees of Marian Lupu’s daughter. The payments were made in July 2014, when Marian Lupu was president of the Democratic Party of Moldova.

Lupu denied that his daughter’s studies were financed by Plahotniuc or anyone else. He explained that, since he did not have a bank account allowing international transfers, he handed the money in cash to his party colleagues engaged in business activities who had accounts capable of making such transfers, asking them to make the payment to the university.

In 2023, Lupu appeared in a new scandal. A former employee of the Court of Accounts accused him of sexual harassment. The head of the CCRM denied the allegations and sued her. The first instance court partially admitted his request, obliging the former employee to publicly retract the claims and pay him moral damages of 10,100 lei. The decision was upheld by the Chisinau Court of Appeal.

In 2025, a year after his mandate as president of the Court of Accounts expired, Lupu took over the leadership of the Movement Respect Moldova Party, a political formation created in 2023 by former democratic deputy Eugeniu Nichiforciuc and a group of former PDM parliamentarians and ministers.