GEOFF BENNETT: The Affordable Care Act faces major rollbacks if the president's big spending and tax cut bill is approved by the Senate.

The proposed changes could affect many of the 24 million Americans enrolled in that insurance marketplace and could leave millions of people without coverage.

The House and Senate versions of the so-called one big, beautiful bill differ, but they have key changes in common, including shortening enrollment periods, requiring additional verification and effectively ending automatic renewals of insurance, making health premiums more expensive and higher cost-sharing, and blocking subsidies for many legal immigrants, refugees and those on student visas.

For more, we're joined now by Sarah Kliff, health policy reporter for The New York Times.

Sarah, thanks so much for being here.

So these changes we mentioned, help us understand how significant they would be for people who rely on the Affordable Care Act for insurance coverage.

SARAH KLIFF, The New York Times: They would be quite significant.

It's estimated by the Congressional Budget Office that about four million people would lose health coverage.

That's about one-sixth of the people who currently get Obamacare.

And it's not this big sweeping repeal that Republicans used to talk about.

It's really a suite of policy tweaks that kind of add - - one source that we talked about this, kind of described it as repeal by paper cut, a lot of small tweaks that add up to millions of people likely losing their insurance under this legislation.

GEOFF BENNETT: And Republicans make the case that these changes are necessary because they say there's so much fraud in the marketplace.

What have you found on that front in your reporting?

SARAH KLIFF: Yes, the marketplace has struggled a little bit with certain kinds of fraudulent enrollment.

A lot of this had to do with brokers kind of enrolling people in ways that weren't quite OK.

The Biden administration did on its way out issue some regulations to crack down on that behavior.

And I think what worries advocates with the Affordable Care Act is that this quest to kind of tamp down on fraud, collect a ton of documents, that it's going to mean a lot of people who really should qualify and do qualify are going to kind of get caught in the crosshairs and lose their insurance because there's just so much more red taping being added in the name of kind of rooting out fraud.

GEOFF BENNETT: The four million people who are estimated to lose their coverage, who are they?

SARAH KLIFF: Yes, about a quarter of those are legal immigrants who currently purchase on the marketplaces.

Under the new legislation, these folks, who include asylees, refugees, they would no longer be able to purchase on the market or to use the subsidies on the marketplace to find affordable coverage.

And then there's a pretty big group of people who just aren't going to comply with the paperwork requirements.

One of the really big changes is just a lot more work to get insurance.

So you have to submit all your original documents to the marketplace, versus how it works currently, where the marketplace will ping all these government databases, kind of check for you if you're eligible.

You have to reenroll each year.

Right now, there's an automatic reenrollment.

So the other folks who are likely to lose coverage are really people who are buying their coverage, but they might not be as on top of their paperwork.

They might not see the renewal notice, and they could end up uninsured that way.

GEOFF BENNETT: Those subsidies you mentioned, many people started getting those tax credits during the pandemic.

What's the Republican argument for discontinuing those?

SARAH KLIFF: Yes, I think the idea is, they feel like it's become too subsidized, that it's almost become too cheap to get insurance, that people should have to pay a little bit more for their coverage.

This was meant to be a pandemic era support, and obviously we have moved on to a different period.

So I think the idea is it got a little too subsidized, and that they want to pull that back, ask folks to chip in a little bit more for their coverage.

GEOFF BENNETT: To your earlier point that the GOP tried to kill the Affordable Care Act legislatively, that didn't work.

I think there were more than 70 votes in the U.S. Congress during President Trump's first term.

Now this effort to dismantle it piece by piece, how effective might that be?

SARAH KLIFF: I think it'll be decently effective.

I don't think it'll disappear.

I think Obamacare is still going to be here.

Enrollment right now is at an all-time high.

It's at 24 million people, which is about quadruple where it was the first year it launched in 2014.

So it's really working quite well right now, a lot of people getting coverage.

I think it'll just get smaller.

You will see fewer people getting coverage.

Premiums might go up, because the people who are most likely not to fill out their paperwork are kind of younger, healthier people who are going to be less attuned to their health insurance, whereas the people who really need it are going to jump through the hoops.

So you might see some destabilization to some level by the fact that you have more expensive people in the marketplaces.

And that drives up premiums for everybody.

GEOFF BENNETT: And when you add these changes to the potential changes coming to the Medicaid system, I mean, what does the health care landscape, the health insurance landscape look like for people who are low to moderate income?

SARAH KLIFF: Yes, you layer in the Medicaid changes and then we're talking about like a fundamental change to our social safety net.

We're getting up to 10 million or so people losing insurance because of the House legislation and because of the expiration of those extra tax credits you mentioned, another five or so million.

So really we'd be looking at the first increase in the uninsured rate in the United States in over a decade.

I think it'd be quite significant when you pair it with the really significant nearly trillion-dollar Medicaid cuts that are contained within this legislation.

GEOFF BENNETT: Sarah Kliff, health policy reporter for The New York Times, thanks again for your time this evening.

We appreciate it.

SARAH KLIFF: Thank you.