The ruling Movement for Socialism failed to attain a supermajority in either chamber—as it had done in the previous assemblies—granting the opposition a higher degree of discretion over decisions requiring the support of two-thirds of legislators.

However, amendments to the regulations of both chambers approved by the preceding legislature shortly before this assembly's formal installation abrogated the two-thirds requirement for numerous parliamentary procedures, leading political analysts to note the effective neutralization of the opposition's ability to operate.

Subsequent disputes and accusations by the opposition of abuse of parliamentary procedure purportedly perpetrated by the ruling party have resulted in disorderly behavior and even physical violence during legislative sessions regarding the election of members to commissions and the passage of controversial bills.

[2] As a result, the MAS was placed in a situation in which it would be forced to negotiate with the opposition on matters requiring two-thirds of the assembly's support, a fact that had not been the case for over a decade, since the opening of the 2010–2015 legislature in January 2010.

Political Scientist Franklin Pareja noted that, without two-thirds, the MAS would no longer be able to circumvent legislative debate and pass laws without discussing with the opposition, as it had grown accustomed to doing in previous years.

However, measures requiring two-thirds of both chambers as established by the Constitution, such as the appointment of the prosecutor general, the ombudsman, the comptroller, or members of the Supreme Electoral Tribunal, remained unchanged.

[3] Outgoing Senator Ciro Zabala [fr] (MAS) explained the new rules as "an administrative change" meant to push aside "obstacles" to Luis Arce's mandate.

[4] Similarly, Creemos leader Luis Fernando Camacho characterized the regulatory amendment as an "outrage", stating: "the MAS will never leave behind its dictatorial impulse".

[6] Newspaper Página Siete reported that, in this way, "[the] MAS [has] neutralize[d] the opposition for five years", primarily due to the fact that the ruling party was now capable of closing legislative debate by a simple majority.

[7] At Arce's inauguration, Mesa and the entire CC caucus left the hemicycle of the Plurinational Legislative Assembly in protest prior to the end of the ceremony.

In a press conference, Mesa announced CC's intent to file an appeal with the Plurinational Constitutional Court (TCP), demanding the unconstitutionality of the annulment of the two-thirds requirement.

[9] In late November, the TCP rejected the motion on technical grounds, arguing that the coalition had not gone through the proper legal channels in the Legislative Assembly before bringing their case to the court.

In a statement, CC characterized its establishment as "an affront to the country" that wastes economic resources in the midst of a health crisis in order to "satisfy the megalomania of Evo Morales".

Senator Rek stated that the decision of its caucus not to attend was due to the fact it had "nothing to celebrate ... because we are cut in our rights and legislative functions, and they do not allow us to participate and influence the laws that are approved".

Outgoing Deputy Amílcar Barral stated that, while it would be difficult, he "would not be surprised if ... some legislators from Civic Community and Creemos ... betray their parties and go to support the MAS".

[2] The first instance of such an occurrence came on 28 January 2021, when Edwin Bazán, head of the Creemos caucus in the Chamber of Deputies, announced the alliance's expulsion of four of its deputies—Tito Caero, Runy Callaú, Sandra Paz, and Omar Rueda—for what he described as "moral turpitude".

[17] The decision came due to the events of a month prior, in which the four expelled deputies presented Rueda as a nominee to the Ethics Commission against Bazán, who was nominated by the rest of the Creemos caucus.

[18] Bazán denounced that, in this way, the MAS achieved a majority on the commission, with three of its own deputies and one dissident to the two of CC, a fact he indicated they would use to intimidate the opposition with sanctions and legal processes.

[17][19] As a result, Bazán announced his alliance's intent to file a lawsuit with the Supreme Electoral Tribunal (TSE) for political transfuge in order to regain the seat.

[24] Creemos Deputy José Carlos Gutiérrez of Santa Cruz contended that the strategy of the MAS was to achieve the suspension of four incumbents in order to allow their UCS substitutes to take the seats.

Additionally, the four Creemos dissidents rejected their caucus' nomination of Oscar Michel to the fourth secretariat, instead promoting the continuation of incumbent secretary Sandra Paz in the position.

Though Mamani sought a second term as president of the lower house, he failed to attain the nomination of the MAS' La Paz caucus, with Hernán Durán winning the vote by a margin of twenty-five to sixteen.

While the MAS managed to resolve its disagreements semi-magnanimously, the opposition's disputes continued much more openly, with CC electing to publicly expel both defecting deputies from its ranks.

The vote took place amid an atmosphere of screams, insults, pushing, and shoving; at one point, deputies poured water on each other while others tore up their ballots denouncing a "legislative coup".

[27][40] For CC Deputy Toribia Lero, instances of political transfuge result in the "weakening of the little democracy that remains in the country" by keeping the legislature "submissive and obedient".

[41] Shortly after the session, MAS deputy Héctor Arce accused his colleague from Creemos, Tatiana Áñez, of grabbing and scratching his neck when he tried to stop her from moving to the front to interrupt the president.

Alarcón denounced that its installation had been called just fifteen minutes in advance, making it impossible for a large part of the opposition to arrive from their respective departments.

Although the MAS took into account some adjustments suggested by the opposition, they were nonetheless criticized for presenting a draft regulation that gave the Mixed Commission complete control over the pre-selection of prospective candidates.

As soon as the session began, CC Senator Silvia Salame of Chuquisaca raised a preliminary motion to establish that the regulation face the approval of two-thirds of the Legislative Assembly.

Each body's general regulations defines a Chamber Directive Board elected each year from among its full members by an absolute majority of those present, respecting gender equity criteria.