When the Office issues a requirement for restriction in a patent application, the applicant must respond with an election, and arguments traversing the restriction if they disagree with it. An applicant cannot petition the restriction at this point and must wait until the restriction is made final. CFR 1.144.

But what happens if the examiner repeatedly enters new restrictions on each action and never makes a restriction final? All is not lost. This issue occurred in US 14/800,061 (currently under appeal). The Office of Petitions confirmed that while the restriction was not final, it was still petitionable as a "repeated" action. From the Petition Decision:

So, if you find yourself subject to repeated and constantly changing restrictions that are never made final, there is a path to obtain review as illustrated by this decision.

This case also illustrates the common errors examiners often make in restrictions, such as making an election of species between claims. As the above decision correctly notes later on, claims are never species. So, an election of species requirement made between claims is per se incorrect.