The Illusion of Speaking for the People
Populism is antithetical to pluralism. Populism identifies the 'majority' as one homogenous 'true people' in opposition to a 'corrupt elite', and when populist governments seek to implement the 'true people's' common will, they upset the vertical and horizontal relationships between branches of government. A populist's approach to democracy is generally majoritarian and illiberal, seeking to ignore, deny or suppress pluralism. This exaltation of a 'true people' creates the central tension between populism and the protection of diversity and pluralism enshrined in the constitutional systems of European Member States. Certainly, each populist party interacts in its own way with the respective country's constitution. However, different variants of populism share common elements that contribute to the formation of an alternative constitutional imagery that is used to create and enhance unchecked decision-making power by the ruling majority. From a comparative perspective, this translates into a common trend towards the centralization of power.
Centralization can be both horizontal and vertical and, when pursued by populists, it has the following features: it is pragmatic, subtle and functional towards charismatic leadership. Horizontal centralization is pursued differently depending on whether populist majorities are large enough to amend the constitution or not. If they do have a large enough majority, populists will not miss this opportunity to change the constitution (this is the path Orbán followed in Hungary after his landslide victory in 2010), but if they don't have a sufficient majority they will implement their policies through changes to ordinary laws and unwritten rules. This is how the PiS government in Poland between 2015-2023 managed to tame the judiciary and its National High Council, as well as capture the Constitutional Court.
Vertical centralization is pursued by populists through the advocacy of sovereignism which, in EU Member States, basically consists of a pushback against supra-national political power. One could assume that multi-level governance is antithetical to sovereignty-based populism, however the pushback is very subtle because populists pragmatically want 'the best of both worlds'. In fact, populists never explicitly request to withdraw from the EU, but prefer to adopt measures that constantly push the boundaries in favor of the nation. Again Poland (under PiS) and Hungary are prime examples.
So, having considered all the above, what role does the constitution have in the populists' pursuit of centralization? First of all, the constitution is transformed from a constraint on power into a 'last bastion' against future assaults by the enemies of the true people. An example of this is Article 3 of the Ninth Amendment to the Hungarian Constitution which protects a child's right to identify with their gender at birth and have an upbringing based on Hungary's constitutional identity and Christian culture. Second, the constitution puts limits to external interference, especially that of the EU, with respect to domestic executive power. The Torubarov Case on refugee status in Hungary is a good example of this. Third, by means of constitutional entrenchment, the constitution limits the role of ordinary courts and reserves the power of adjudication to a (captured) constitutional court (again Orbán's Hungary is an example of this).
One can thus draw the conclusion that populist governments have undoubtedly had an adverse impact on the democratic resilience of constitutional systems of the Member States of the European Union. Indeed, as Timothy Garton Ash recently pointed out, even if liberal democrats return to power (as recently occurred in Poland), they will have to 'resist the temptation of simply turning the tables, installing their own partisan loyalists instead of the other lot' without properly restoring liberal democracy. Of course, this is no easy feat because constitutional changes carried out by populists imply that the constitutional system may resist attempts to revert populist changes, making 'democratic restoration' an extremely arduous task.