BUENOS AIRES — Mauricio Macri clinched Argentina’s presidency last month by tapping into voters’ fatigue with a leftist political movement that had governed for more than 12 years. Campaigning on a platform of change, and promising to unite feuding factions while largely dodging specific policy proposals, Mr. Macri took 51 percent of the vote.

But now, just three weeks into his four-year term, Mr. Macri’s sweeping economic changes are roiling Argentina, accentuating the divide he wanted to bridge and leading some Argentines to doubt whether he will be a change for the better.

“They voted for him to get the government out, but they didn’t think about what was going to come,” said Damián Raspa, 36, a machine worker at an electronics factory from La Matanza, a working-class district of greater Buenos Aires where Mr. Macri lost heavily to his main rival in the election, Daniel Scioli.

Mr. Raspa, a father of two who earns about $615 a month, said he would now have to make his salary stretch because Mr. Macri’s government devalued the peso by nearly 30 percent in mid-December, to more than 13 pesos to the dollar from 9.8; it later strengthened slightly.