Socialist candidate Pedro Castillo continued to regain ground among voters, a poll showed on Sunday, boosting his lead over conservative contender Keiko Fujimori two weeks ahead of Peru’s presidential election.

Castillo, an elementary school teacher seeking to implement new taxes and royalties on the mining sector, obtained 44.8% support in the survey of the Institute of Peruvian Studies (IEP), while Fujimori, a business-friendly conservative, netted 34.4%.

The poll of 1,208 people was conducted for Peru’s La Republica newspaper on May 20-21 and had a margin of error of 2.8 percentage points.

Castillo, who had begun to flounder in polls earlier in May, has gained significant ground since the same IEP survey in mid-May, in which he obtained 36.5% among intended voters and Fujimori 29.6%.

On Saturday, protesters marched in Lima and other major Peruvian cities toting banners and shouting the slogan “Fujimori never again.” Fujimori’s father, the former president Alberto Fujimori, is in prison over corruption charges.

Castillo, who stormed into the run-off with Fujimori following a win in a shock first-round election, has strong support among Peru´s largely poor, interior rural communities. Marketwatchers, however, view his candidacy as a potential threat to industry in the world´s No.2 copper producer.

The Sunday poll also indicated that 13% intend to vote blank or annul their vote in the June 6 ballot, while 5.1% were still undecided.