The Trump administration has put a halt on the Obamacare outreach ads, Politico reported Thursday night, five days before the law’s open enrollment period ends.

According to the report, the administration will also be “halting all media outreach designed to spur enrollment in the days leading up to the Jan. 31 deadline. Emails are no longer being sent out to individuals who visited HealthCare.gov, the enrollment website, to encourage them to finish signing up.”

These five days are a really bad time to have no outreach for the health law — and there’s a simple graph that helps explain why.

For Obamacare to work, it needs a lot of young people to sign up. Young adults typically have lower health care costs, so they can help balance out the hefty medical bills of older enrollees.

In previous open enrollments, we’ve seen young people wait until the end of the sign-up period to purchase coverage. And that makes sense: When you’re healthy, you’re not as worried about making sure you have insurance.

You can see it in this graph, which shows young people as a percentage of Obamacare enrollees in the last open enrollment period.

When open enrollment started in 2015, young adults were less than a quarter of enrollees. By the January 31 deadline, they were up to 37 percent.

Young people are critical to making the Obamacare marketplaces work. Any health insurance pool needs relatively healthy people to jump in, to balance out the higher medical bills that older enrollees tend to have.

With less outreach at the very end of the open enrollment period, former Obamacare officials expect they’ll have fewer sign-ups from young adults. This is what Lori Lodes, who helped run Obamacare outreach for a few years, had to say about it on Twitter:

There have been many Republican claims that Obamacare is “collapsing” lately — despite forecasts from independent agencies like the Congressional Budget Office that estimate the law’s marketplaces are small but stable.

A move like this, however, could cause disruption by making it harder for the health care law to reach the exact people the marketplaces need the most.