Hospice fraud in California has been remarkably brazen. Medicare recipients have been signed up for care without their knowledge by thieves who stole their identities. Providers have paid kickbacks to people to enroll even though they aren’t terminally ill and don’t qualify. Sham companies have fabricated lists of employees.

The schemes have been an irresistible political target for President Trump, who mentioned California as a top offender when he created a task force last month to root out corruption in federally funded programs. He said that he believed that fraud in the nation’s most populous state was “10 times worse” than anywhere else.

But long before Mr. Trump weighed in, state investigators had uncovered rampant fraud in California’s hospice system on their own. For years, state and federal officials had been taking steps to combat abuses, and the state has stopped issuing new hospice licenses.

Despite the actions underway, Mr. Trump has made hospice fraud in California a new political flashpoint.

In recent weeks, nearly every day has brought dueling announcements from Democrats and Republicans about busted Medicare abuse schemes or calls for legislative sessions to examine fraud in the state. Dr. Mehmet Oz, the former talk show host who now runs the Centers for Medicare and Medicaid Services, has been an emissary of the Trump administration’s campaign against California, visiting the state and posting videos decrying health care fraud there. On Tuesday, a House committee held a special hearing on Medicare fraud with a focus on hospice abuse in California.