When Jean-Claude Juncker became European Commission president five years ago, he confronted formidable challenges, but the test faced by his successor, Ursula von der Leyen, is even more complex.

As Von der Leyen underscored in her “agenda for Europe,” one of her top priorities must be to carry out “a new push for European democracy.”

She can strengthen the EU’s democratic legitimacy in two ways: on the output side, by making sure that the EU delivers on citizens’ expectations at a time of rapid change and escalating external challenges, and on the input side, by fostering constructive cooperation with the European Parliament.

Yet, today, the European Parliament is highly fragmented and polarized, making a stable, pro-European coalition difficult to build. To pass legislation, Von der Leyen would need the support of the Conservatives and Social Democrats, as well as robust and productive working relationships with the Greens and the Liberals. She would probably have to form flexible coalitions in specific areas, which would be time-consuming and increases the risk of political failure on contentious issues.

After the recent elections, for the first time in the European Parliament’s history, pro-European factions — the conservative European People’s Party, the Social Democrats, the Greens and the Liberals — met to create a cross-party political program. Yet the process stalled, as the parliament could not agree on its own candidate for the office of commission president, and a four-party “coalition agreement” is no longer on the table.

Von der Leyen should nonetheless engage the parliament politically as much as she can, beginning with the priorities included in the mission letters that she must send to commissioners. These priorities should be shaped by discussions with the newly elected chairs of the parliamentary groups.

Fostering constructive cooperation with the parliament would require credible implementation of a de facto right of initiative for the parliament, regular dialogue with the president and the enduring commitment of every single commissioner.

Von der Leyen must be able to rely on her team to help her navigate the complex political environment not only in the parliament, but also in the European Council, and to guide her efforts to engage the European public in a debate on the EU’s future.

That is why Von der Leyen must ensure that when tailoring the commissioners’ portfolios, inter-institutional relations are given sufficient weight.

In the previous commission, Vice President Frans Timmermans handled such relations as part of his vast portfolio. In the new commission, inter-institutional relations — together with democratization — should form a commissioner’s full portfolio.

That commissioner’s task would be hugely important, and thus should be undertaken by an experienced policymaker — ideally someone who has worked at the national and European levels, in the European Parliament and with the council.

Given Von der Leyen’s party affiliation, a Social Democrat would be a good choice, although whoever is chosen would need to be able to work across party lines.

Working directly with Von der Leyen and the commission’s vice presidents, this commissioner should manage overall relations with the European Parliament and the General Affairs Council, while also helping to coordinate each individual commissioner’s interactions with the parliament. This portfolio would include preparation of the commission’s annual and pluri-annual programs and, in particular, its joint declaration with the parliament on annual legislative priorities.