Millions of electricity customers in President Donald Trump’s adopted home state of Florida will see their bills rise, after a regulatory board approved what environmental advocates say is one of the largest utility rate increases in the state’s history.

The price hike will affect an estimated 12 million Floridians — roughly half the state’s population — at a time when voters are citing economic concerns as a top issue, and as Democrats and Republicans brace for a debate over affordability in the intensifying midterm battle to control Congress.

The Florida Public Service Commission approved the rate increase Thursday for Florida Power & Light, the state’s largest power company, over the strong objections of advocates for the elderly, conservation groups, and the state-appointed advocate for Florida ratepayers, who called the proposal “disproportionately favorable” to corporate interests.

In a statement, FPL said the rate increase is needed to make “smart, necessary investments in the grid to power Florida’s growth,” while keeping customers’ bills “well below the national average.”

Here’s what to know.