Harris, the US vice-president, said she would not stop fracking if elected president, reversing her previous opposition to much of the current US oil and gas production technology. "As vice-president, I have not banned fracking," Harris said in an interview on Thursday, her most explicit statement on the issue since becoming a Democratic candidate. "As president, I will not ban fracking." Earlier, Trump said Harris had led the US campaign to "ban fracking" and called on Pennsylvania voters to vote for him.