LONDON, June 3 Reuters Mexico39;s peso slipped nearly 3 against the dollar on Monday after Claudia Sheinbaum won a landslide victory in the presidential election and the ruling coalition looked poised for a supermajority that markets fear could bring constitutional change.

The peso hit a fresh fiveweek trough of 17.5020 to the dollar, its worst drop since September 2020, LSEG data showed.

The latest losses mean the currency has weakened 2.4 since the start of the year, a sharp turnaround for the unit, which was, until recently, one of the few emerging markets currencies to have gained ground against a strong dollar.

In Mexico, the question is whether the Morena party has done so well that it could command a supermajority and try to pursue market nonfriendly policies of constitutional reform, said Chris Turner, global head of markets at ING.

Sheinbaum, a climate scientist and former mayor of Mexico City, won the presidency with between 58.3 and 60.7 of the vote, according to a rapid sample count by the electoral authority, in what is set to be the highest vote percentage in Mexico39;s democratic history.

Her victory had been widely anticipated, but the scale of Morena39;s gains and the prospect of the ruling coalition potentially clinching a super majority has taken markets by surprise.

Securing a twothirds super majority in both houses of Congress would allow the group to pass constitutional reforms without opposition support.

That would enable Sheinbaum and…