Obamacare enrollment starts in 25 days. Nine in 10 uninsured people don’t know.

Here’s a big challenge for Obamacare: About three-quarters of uninsured American have no idea that the law’s sign-up period is just around the corner.

The Kaiser Family Foundation published a new survey Tuesday showing that 76 percent of uninsured adults didn’t know when the health care law’s open enrollment period started. 11 percent were able to correctly identify open enrollment as starting in November while the rest guessed other dates.

And when Kaiser further surveyed uninsured Americans on the health care law, they found relatively low levels of awareness about the different parts of Obamacare — like about the financial assistance that exists to buy coverage or about the online marketplaces for shopping.

Open enrollment starts in 25 days, on November 15. And the Kaiser data suggests that, just like last year, there is a big gap in public awareness of how the law works — or when people can shop.