GUATEMALA CITY (AP) — The struggle to certify the results of Guatemala’s first-round presidential election has suffered another reverse after the chief justice of the Supreme Court issued an order blocking the certification.

Chief Justice Silvia Valdés Quezada issued the unusual order late Friday. She stipulated the process could not go forward until the electoral authorities that conducted a review of vote tally sheets from the June 25 election reported back to her on their methods and any inconsistencies found.

Valdés Quezada said they had to do that within 12 hours.

The reviews witnessed by the AP found improperly marked or counted votes amounted to less than 1% of the total, not enough to change the results.

Experts said Saturday that Valdés Quezada's order was strange because she was the only justice to sign it. According to normal procedure, it should have been signed by all 13 justices.

“She alone is suspending the electoral process," said constitutional lawyer Alejandro Balsells.

Ovidio Orellana, the former head of Guatemala's bar association, wrote in his social media accounts that such an order “should be signed by all the magistrates.”

If candidates Sandra Torres and upstart Bernardo Arévalo remain the two highest vote-getters in the re-examination, it will boost the likelihood that their one-two finish in the first round will stand and that the two candidates will head to a run-off election Aug. 20.

The Supreme Electoral Tribunal said in a statement Friday that the review “confirms the preliminary results published on June 25,” and urged political parties “to accept with maturity the election results, which represent the legitimate will of the people.”

Edie Cux, director of Accion Ciudadana, the local chapter of nongovernmental organization Transparency International, said Friday that the electoral tribunal must now endorse the conclusions from several days of reviews of the tally sheets compiled by 152 of the more than 122,000 polling stations.

“The result has not changed, the period for the review has practically closed and as established by the law they must now certify the results and assign positions looking ahead to the second election round,” Cux said.

David de León, spokesman for the electoral tribunal, said the panel hoped to certify the results in the coming week once the challenged tallies are received and the necessary changes made to the vote totals.

The vote tallies were announced soon after the June 25 elections, but the Constitutional Court — the country's highest — suspended the certification of official election results, granting a temporary injunction to 10 parties — one later dropped out — that challenged the results, saying they suspected they were robbed of votes.

The matter now lies with the Supreme Court of Justice, which the Constitutional Court designated to handle the case.

In an extremely crowded field, neither Arévalo nor Torres got 50% of the vote, so they would be scheduled to face each other in runoff vote on Aug. 20.

Arévalo, of the progressive Seed Movement party, was a surprise, as he had not been polling among the leading candidates. Torres, the candidate for the conservative UNE party, is making her third bid for the presidency.

The court challenge had awoken fears that political forces might be seeking to invalidate the June 25 elections.

On Sunday, U.S. Secretary of State Antony Blinken said in a statement that the U.S. government endorsed the conclusions of numerous domestic and international election observation groups, “which found that the published results in Guatemala’s most highly observed election matched with their observations across the country.”

“The United States supports the Guatemalan people’s constitutional right to elect their leaders via free and fair elections and is deeply concerned by efforts that interfere with the June 25 election result,” the statement said.

Among the parties challenging the results are those of three candidates who were polling among the leaders before election day, but ended up getting less than 8% of the vote each. However, Torres’ party also asked for a review of the voting tallies.