• The Mexican peso was down as much as 1.21% versus the dollar early Friday.
  • The peso has been weakening this week amid Mexico’s heated presidential campaign, despite being one of the best-performing currencies against the dollar in 2018.
  • Follow the peso in real time here.

The Mexican peso fell further Friday, threatening its place as the best-performing major currency against the US dollar this year, as political uncertainty around the country’s heated presidential campaign and NAFTA negotiations rolls on.

The currency was down 1.21% versus the US dollar at 10:34 a.m. ET. On Wednesday, it plunged about 2% against the greenback to a three-week low.

The dropoff comes ahead of Mexico’s presidential debate this weekend.

Former Mexico City mayor Andres Manuel Lopez Obrador – a staunch leftist whose election could ratchet up tensions between the US and Mexico – recently widened his already double-digit lead in the race. A poll released Wednesday showed Lopez Obrador 22 points ahead of his nearest opponent, Ricardo Anaya.

"During the campaign, he's floated populist-leaning proposals including the rollback of foreign participation in Mexico's energy sector and increased social spending," Claudia Ceja, Mexico City-based analyst at BBVA, told Bloomberg.

Adding to uncertainty, Mexican officials are in the midst of NAFTA negotiations. The country's foreign minister and economy minister are meeting with members of the Trump administration this week to push for an early deal.

The peso is up more than 5% against the greenback since January.