Senator Alan Peter Cayetano has been courting controversy for as long as anyone can remember. When he was Speaker of the House, he was infamously involved in a leadership dispute that became ugly because of his refusal to honor the “gentleman’s agreement” brokered by then-President Rodrigo Duterte.

Under this term-sharing deal, he was supposed to lead the House for 15 months, after which Rep. Lord Allan Velasco would take over for the remaining 21 months. Unsurprisingly, though, this Peter denied “the Lord” more than three times, resisting efforts to step down from office.

Although he dramatically offered his resignation, he instructed his allies to reject it so he could abruptly suspend the plenary session until mid-November. This allowed him to prevent the scheduled speakership transition date.

Because of this, Velasco’s supporters were forced to convene an unprecedented remote session at the Celebrity Sports Plaza, where a majority of lawmakers declared the speakership vacant and elected Velasco as the new Speaker.

Well, six years later, it’s déjà vu all over again for the embattled Senate president. Unlike in the House, though, he was just warming up when the 12 senators present during the 3 June session voted to oust the Cayetano-led leadership and install Win Gatchalian as acting Senate president. Relying on the Avelino v. Cuenco doctrine, the new majority argued that 12 constituted a quorum out of 22 active Senate members.

As anticipated, Cayetano has aggressively challenged the validity of the vote and insisted that he remains the legitimate, legal and moral Senate president. He argued that, under Senate rules, removing the Senate president requires a minimum of 13 votes, rather than the 12 that voted to vacate the positions.

To be honest, Cayetano is on the losing end here. Since the 3 June session was presumptively regular because it was conducted in the senators’ official capacity as legislators, his only remedy is to file a case in court. Unless he does that, he cannot rebut that presumption.

However, he said he would not do so because filing a case would mean recognizing the presumptive validity of the plenary session. At some point, though, he may have no other choice. Right now, things are still manageable since the Senate has adjourned sine die and therefore has no other business except the occasional committee hearings held here and there. But when the impeachment trial commences, confusion over who should serve as presiding officer could create chaos.

When that time comes, Cayetano may not be able to flex his muscle since the Gatchalian-led majority enjoys the support of the administration, whose resources could be used to stifle and cripple him. Thus, initiating a case now may be the only way to salvage his situation.

Unless, of course, another senator from his group transfers to the new majority. Then it’s game over.