In congressional Republicans' latest move to strip healthcare from millions of Americans, several news outlets reported on Tuesday that party leaders in the Senate are adding a provision to their tax bill to repeal the Affordable Care Act's (ACA) individual mandate, which requires all citizens to have health insurance coverage or pay a penalty fee.

The nonpartisan Congressional Budget Office (CBO) estimates that repealing the mandate would, over the next decade, cause 13 million people to lose their coverage, but also reduce federal deficits by more than $300 billion. That reduction is key to the Republicans' tax bill, which cannot add more than $1.5 trillion to federal deficits.

As Chad Bolt, Indivisible's policy manager, explained in a series of tweets, Senate Republicans are motivated to repeal the mandate not only to fulfill their campaign pledges—and repeated demands from Sens. Rand Paul (R-Ky.) and Tom Cotton (R-Ark.)—but also to free up that $300 billion to more quickly give corporations larger tax breaks.

If fewer people buy health insurance through the exchange, less $ is used to help them afford coverage w tax credits. Rs want to take that savings and 1. start corporate tax cuts sooner or 2. make corporate tax cuts bigger or 3. both. 5/ — Chad Bolt (@chadderr) November 14, 2017

Ben Wikler, MoveOn.org's Washington director, also highlighted the link between the tax cuts and the individual mandate, and called the proposal "disgusting."

The GOP tax bill is now straight-up "take away your health care to pay for tax cuts for corporations." Fight accordingly. — Ben Wikler (@benwikler) November 14, 2017

Wikler broke down how the proposal would likely roll out and impact the national healthcare system.

How new plan works:

1. GOP ends Obamacare’s individual mandate

2. Fewer healthy people buy insurance

3. Premiums shoot up for everyone else

4. Millions can’t afford insurance who want it

5. Govt saves $ on subsidies

6. $ goes to corporations & rich people — Ben Wikler (@benwikler) November 14, 2017

The addition to the Senate Republican tax plan alarmed Democratic lawmakers, healthcare advocates, and others.

BREAKING: Tax bill will repeal the individual mandate:

- 13 million more uninsured

- $1,990 premium tax

- Insurer exodus from markets

ALL TO PAY FOR TAX CUTS FOR CORPORATIONS AND MILLIONAIRES — Topher Spiro (@TopherSpiro) November 14, 2017

Somewhere someone said "this tax plan can't get worse" and now we see it can. It wouldn't be 2017 if the GOP didn't try to sneak in an attempt to repeal the individual mandate of Obamacare. https://t.co/sWBroDXVhO — Steve Westly (@SteveWestly) November 14, 2017

Republicans now adding repeal of Obamacare mandate to tax bill. So they want to raise taxes on middle class families & destroy insurance coverage for millions--all to cut taxes on the wealthy. How will this form of populism play? — David Corn (@DavidCornDC) November 14, 2017

Republicans just can't help themselves - again and again, they propose sweeping legislation that threatens to strip healthcare from millions who need it the most. Even this tax bill. We've got to defeat this #GOPTaxScam. https://t.co/GxBXgHTBD6 — Rep. Pramila Jayapal (@RepJayapal) November 14, 2017

Shortly after news broke about the update to the Senate bill, a collective of major industry groups representing insurers, hospitals, and doctors released a letter (pdf) to congressional leaders of both parties, urging them to maintain the individual mandate, and warning of the "serious consequences if Congress simply repeals the mandate"—most notably, that millions of Americans "will be uninsured or face higher premiums, challenging their ability to access the care they need."