Nearly half of the 17 insurance marketplaces set up by the states and the District under President Obama’s health law are struggling financially, presenting state officials with an unexpected and serious challenge five years after the passage of the landmark Affordable Care Act.

Many of the online exchanges are wrestling with surging costs, especially for balky technology and expensive customer-call centers — and tepid enrollment numbers. To ease the fiscal distress, officials are considering raising fees on insurers, sharing costs with other states and pressing state lawmakers for cash infusions. Some are weighing turning over part or all of their troubled marketplaces to the federal exchange, HealthCare.gov, which is now working smoothly.