President Donald Trump admitted on Tuesday that the tax bill Republicans passed last week would essentially sabotage the Affordable Care Act, the health care plan better known as Obamacare.

“Based on the fact that the very unfair and unpopular individual mandate has been terminated as part of our tax cut bill, which essentially repeals (over time) Obamacare, the Democrats and Republicans will eventually come together and develop a great new health care plan!” Trump tweeted this morning.

Trump’s tweet comes as it was revealed that Obamacare saw robust sign-up numbers — despite the fact that his administration shortened the open enrollment period and slashed the advertising budget intended to educate Americans on how to sign up for Obamacare plans.

Republicans tried multiple times this year to repeal Obamacare, but all of the party’s straight repeal efforts failed, drawing an outcry by the public, a majority of whom now support Obamacare.

Yet, in their tax bill, Republicans successfully repealed Obamacare’s individual mandate. The mandate is a key tenet of the law, intended to incentivize young and healthy people to sign up for health care, which lowers the cost of insurance premiums as it broadens the pool of people in the insurance market.

Without the individual mandate, 13 million more people are expected to go uninsured over the next decade, and the cost of insurance premiums is expected to skyrocket by about 10% per year, according to an analysis by the nonpartisan Congressional Budget Office.

Before signing the bill, Trump said he advised Republicans not to talk about the fact that the tax legislation repealed the mandate, because he didn’t want a public outcry that could spike the bill.

“I told people specifically, be quiet with the fake news media because I don’t want them talking too much about it because I didn’t know how people — but now that it’s approved I can say, the individual mandate on health care, where you had to pay not to have insurance — okay think of that one, you paid not to have insurance — the individual mandate has been repealed,” Trump said before a cabinet meeting on Dec. 20.

Increased health insurance premiums could render the tax cut some low-income families receive moot.

Given how unpopular the GOP’s health care repeal effort went, another attempt at health care could further diminish Republican chances in the 2018 midterm elections.