Premiums will go up sharply next year under President Barack Obama’s health care law, and many consumers will be down to just one insurer, the administration confirmed Monday. That’s sure to stoke another “Obamacare” controversy days before a presidential election. Before taxpayer-provided subsidies, premiums for a midlevel benchmark plan will increase an average of 25 percent across the 39 states served by the federally run online market, according to a report from the Department of Health and Human Services. Some states will see much bigger jumps, others less.Moreover, about 1 in 5 consumers will have plans only from a single insurer to pick from, after major national carriers such as UnitedHealth Group, Humana and Aetna scaled back their roles. “Consumers will be faced this year with not only big premium increases but also with a declining number of insurers participating, and that will lead to a tumultuous open enrollment period,” said Larry Levitt, who tracks the health care law for the nonpartisan Kaiser Family Foundation. Republicans pounced on the numbers as a warning that insurance markets created by the 2010 health overhaul are teetering toward a “death spiral.” Sign-up season starts Nov. 1, about a week before national elections in which the GOP remains committed to a full repeal. “It’s over for Obamacare,” Republican presidential candidate Donald Trump said at a campaign rally Monday evening in Tampa, Florida. Trump said his Democratic rival, Hillary Clinton, “wants to double down and make it more expensive and it’s not gonna work. … Our country can’t afford it, you can’t afford it.” He promised his own plan would deliver “great health care at a fraction of the cost.” The new numbers aren’t too surprising, said Sen. Orrin Hatch, R-Utah, who chairs a committee that oversees the law. It “does little to dispel the notion we are seeing the law implode at the expense of middle-class families.” HHS essentially confirmed state-by-state reports that have been coming in for months. Window shopping for plans and premiums is already available through HealthCare.gov.