GUATEMALA CITY (AP) — Guatemala’s highest court has upheld a move by prosecutors to suspend the political party of President-elect Bernardo Arévalo over alleged voter and registration fraud, a move the incoming leader denounces as a “coup.”

Arévalo and electoral authorities had challenged the suspension in late August, arguing that the allegations of voter or registration fraud are criminal charges and that by suspending the party the prosecutors were intruding on electoral issues.

The Constitutional Court ruled Thursday that even though the case involves criminal accusations, prosecutors can impose measures that have electoral effects.

Without his Seed Movement party, Arévalo may be hamstrung after he takes office Jan. 14. Arévalo says politically motivated prosecutors are carrying out a “coup” and are trying to overturn his victory in August elections. Prosecutors say some of the signatures used to register Arévalo’s party may have been false.

Thousands of people blocked highways across Guatemala this week in reaction to the attorney general’s office seizing vote tallies from electoral authorities. The seizure was part of the continuing investigations into accusations of voting fraud that observers say are politically motivated.

Indigenous groups and rural farm workers stalled traffic on major transportation arteries over what they see as a violation of voters’ will.

The Organization of American States observation mission said prosecutors’ actions appeared to be aimed at keeping Arévalo from taking office.

Arévalo had a surprisingly strong showing in the first round of Guatemala’s presidential election in June, building support with an anti-corruption campaign that attracted frustrated voters, and he won with nearly 61% of the vote in the August run-off.

Independent election observers have said that they did not see evidence of fraud that would have affected the results in either round of voting.