Efforts by insurers to boost premiums are the latest evidence that President Barack Obama’s health care law “just doesn’t work” and must be replaced, the Republican chairman of the House Ways and Means Committee said Wednesday.

Rep. Paul Ryan of Wisconsin launched the GOP’s latest attack against the health care overhaul as Health and Human Services Secretary Sylvia Burwell defended it before his committee. Their conflicting views underscored that Obama’s 5-year-old law remains a partisan flashpoint, likely to reverberate through next year’s presidential and congressional elections.