The monarch's power was limited in favor of a sizable noble class. Each new king had to pledge to uphold the Henrician Articles, which were the basis of Poland's political system (and included near-unprecedented guarantees of religious tolerance). Over time, the Henrician Articles were merged with the Pacta Conventa, specific pledges agreed to by the king-elect. From that point onwards, the king was effectively a partner with the noble class and was constantly supervised by a group of senators. The Sejm could veto the king on important matters, including legislation (the adoption of new laws), foreign affairs, declaration of war, and taxation (changes of existing taxes or the levying of new ones).