Democrats sued Georgia state election officials on Monday, alleging new rules that could allow local officials to delay certification of November’s presidential results were illegal.

The lawsuit was filed in the superior court of Fulton county by local Georgia Democratic politicians, the Democratic National Committee and the Democratic party of Georgia. It says the rules approved by the Republican-controlled Georgia state election board this month were intended to give individual county election officials the ability to delay or cancel the certification of votes.

The lawsuit says the new rules “introduce substantial uncertainty in the post-election process and – if interpreted as their drafters have suggested – invite chaos by establishing new processes at odds with existing statutory duties”.

The Georgia secretary of state’s office, which oversees the board, did not respond to requests for comment.

Last week, the five-member Georgia election board, which includes three conservative members championed by Republican presidential candidate Donald Trump, voted 3-2 to empower county election board members to investigate any discrepancies between the number of cast ballots and the number of voters in each precinct before certification.

Such mismatches are not uncommon and are not typically evidence of fraud, according to voting rights advocates, who say that rule could permit individual board members to intentionally delay approval of the results.

The board has also in recent weeks approved a separate rule that county election boards conduct a “reasonable inquiry” into any irregularities before certifying the results. The rule did not define “reasonable” or set a particular deadline for completing the inquiry.

The Democrats’ lawsuit says it is established law that it is the responsibility of the judicial system, not individual county election officials, to resolve allegations of voter fraud.

The former president has falsely claimed for years that the 2020 election was rigged by fraud.

His infamous January 2021 phone call in which he asked Georgia’s top election official, Republican secretary of state Brad Raffensperger, to “find” enough votes to sway the outcome helped lead to Trump’s pending indictment on state charges.

Voter fraud in the US is vanishingly rare, research shows.

Trump faces Kamala Harris, the Democratic presidential candidate, in the 5 November election. Polls show a close race, with Georgia among seven states likely to determine the outcome.