Welcome to Health Reform Watch, Sarah Kliff’s regular look at how the Affordable Care Act is changing the American health-care system — and being changed by it. You can reach Sarah with questions, comments and suggestions here. Check back every Monday, Wednesday and Friday afternoon for the latest edition, and read previous columns here.

Days until marketplaces launch: 8.   

(J. Scott Applewhite/AP)

The federal government could shut down Oct. 1 if Congress doesn't, some time between now and then, pass new funding legislation.

Obamacare's marketplaces, meanwhile, would still open up for business.

While the health-care law is at the center of the government shutdown fight – Republicans want to defund the law, the White House, predictably, does not – the Affordable Care Act could actually function during a stoppage in federal funding remarkably well. The law's biggest programs, like the new online marketplaces and health insurance subsidies, would by-and-large move forward without much hindrance at all.

That's the take from the Congressional Research Service, which looked into the issue last summer, when Republicans began talking about shutting down the government rather than funding Obamacare.

"It appears that substantial ACA implementation might continue during a lapse in annual appropriations that resulted in a temporary government shutdown," CRS analysts wrote in that report.

This largely has to do with how the big pieces of Obamacare are funded. The law uses mandatory funds for its really big programs. That includes the new online marketplaces, known as exchanges, where uninsured people will be able to shop for coverage. The Medicaid expansion is funded with mandatory funding, as are the billions in federal tax credits to help with purchasing coverage.

Those mandatory funds were appropriated in the Affordable Care Act and, without repealing Obamacare, legislators cannot touch them. Even in the face of a government shutdown, this is the spending that sticks around.

So, Obamacare is largely insulated from yearly budget negotiations. Or, if you want to put it in CRS-speak, the agency believes that Health and Human Services could rely on "sources of funding other than annual discretionary appropriations to support implementation activities, including multiple-year and non-year discretionary funds still available for obligation as well as mandatory funds."

Putting the mandatory funding aside for a moment, the Congressional Research Service also points out that Health and Human Services isn't really counting on additional funding from Congress. The agency has requested – and Congress has repeatedly denied – additional money to set up the health-care law. Without that, it's identified other funding sources that it can use to make implementation works.

This includes everything from money in the Public Health and Prevention Fund (which has permanent appropriations for the next decade) and transfers from other HHS accounts. In other words, HHS already operates under the presumption that it's not getting additional Obamacare funding from Congress. Agency officials know that Republicans aren't going to help fund a law they want to repeal. So they've already built a budget that doesn't rely on additional federal funds.

Regulations require the new health law marketplaces to open next Tuesday, Oct. 1. That could be the same day that the federal government shuts down. But either way, the opening date really doesn't change. Whether the government is open or not, the health-care law is near certainly moving forward.

KLIFF NOTES: Top health policy reads from around the Web.

Exchange plans will have fewer doctor choices. "Federal officials often say that health insurance will cost consumers less than expected under President Obama’s health-care law. But they rarely mention one big reason: Many insurers are significantly limiting the choices of doctors and hospitals available to consumers." Robert Pear in the New York Times

Can Hollywood save Obamacare. "Wedged into the blotter on Mike Farah's desk at the Funny or Die studios in Hollywood is an index card with a list — wrangling talent, polishing scripts and arranging shoots — long enough to keep the comedy Web site executive fully occupied. But these tasks are part of a different quest: the campaign to ensure the success of President Obama's healthcare law." Maeve Reston in the Los Angeles Times.

Groups are still lobbying to change Obamacare. "While conservatives on Capitol Hill are waging a last-ditch battle to scuttle the Affordable Care Act, some powerful Washington groups that were among the legislation’s loudest critics are now trying to shape the law and how it’s carried out, an acknowledgment that they need to learn to live with the landmark initiative. Other players that have been more supportive of the law are also engaged in a lobbying push, pressing Congress and federal agencies to refine provisions." Holly Yeager in The Washington Post