The US supreme court went out of its way on Monday to help Louisiana Republicans redraw their congressional maps before this year’s midterm elections by allowing a recent ruling that gutted a key part of the Voting Rights Act to take effect ahead of schedule.

The procedural move comes less than a week after the court’s landmark decision striking down Louisiana’s congressional map and gutting section 2 of the Voting Rights Act. Usually, the court waits 32 days to formally issue its judgment to the lower court. Last week, Louisiana asked the court to speed up that process, citing the urgency with which it needed to redraw its congressional maps. On Monday, the court agreed to do so.

“The date scheduled for the beginning of early voting in the primary election has already passed. The congressional districting map enacted by the legislature has been held to be unconstitutional, and the general election will be held in just six months,” Justice Samuel Alito wrote.

The decision is likely to offer more legal cover to Louisiana Republicans, who took the extraordinary step of cancelling the 16 May primary for Congress after mail-in ballots had already gone out to overseas voters. There is ongoing litigation challenging that decision, and the supreme court expediting its judgment could bolster Louisiana’s legal arguments for the need to hold new elections.

Dissenting from the court’s decision on Monday, Justice Ketanji Brown Jackson ripped the court from departing from its usual procedure. There were only two times in the last 25 years, she wrote, when the court had expedited its ruling.

“To avoid the appearance of partiality here, we could, as per usual, opt to stay on the sidelines and take no position by applying our default procedures. But, today, the Court chooses the opposite. Not content to have decided the law, it now takes steps to influence its implementation,” she wrote. “The Court’s decision to buck our usual practice under Rule 45.3 and issue the judgment forthwith is tantamount to an approval of Louisiana’s rush to pause the ongoing election in order to pass a new map.”

In searing language, she said the court’s majority “unshackles itself from both constraints today and dives into the fray. And just like that, those principles give way to power.”

That accusation prompted a forceful response from Alito, who wrote an opinion joined by fellow conservatives Clarence Thomas and Neil Gorsuch. Jackson’s language was “baseless and insulting”, he wrote.

“The dissent goes on to claim that our decision represents an unprincipled use of power. That is a groundless and utterly irresponsible charge,” he wrote. “What principle has the Court violated? The principle that Rule 45.3’s 32-day default period should never be shortened even when there is good reason to do so? The principle that we should never take any action that might unjustifiably be criticized as partisan?”