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: 41. 

Just about every poll on Obamacare will show you the same thing: There's a huge partisan split on the health care law. Most Democrats support it, most Republicans oppose it and independents fall somewhere in the middle.

That partisan divide, however, hasn't necessarily translated into how Americans use the law. A new poll finds that young Republicans are more likely to have health coverage through their parents' policy than young Democrats, an option widely expanded under the Affordable Care Act.

The poll comes from the Commonwealth Foundation, which has spent two years tracking how adults between the ages of 19 and 25 are reacting to the Affordable Care Act. Beginning in 2010, the health care law allowed young adults up to age 26 to stay covered under their parents' health plans.

The Commonwealth Foundation estimates that of the 15 million young adults that have  insurance coverage through a parent, 7.8 million would not have qualified without this policy.

This dovetails with separate Census Bureau data which also finds an uptick in young adults' insurance coverage, one that doesn't show up in other demographics.

The Commonwealth Fund wanted to dig beyond that and figure out who these people were, the ones who had gained coverage under this health law provision. That's where they found that since 2011, young Republicans have had a higher rate of enrollment in their parents' health insurance plans than young Democrats.

Right now, 45 percent of young Democrats receive coverage through their parents' plan, compared to 63 percent of young Republicans.

Rates have also been higher among more affluent young adults and those with college degrees, who are more likely to have access to a parent's insurance plan in the first place.

It's worth keeping in mind that not all of this coverage is due to the Affordable Care Act. By the Commonwealth's estimate, only about half of the 15 million young adults on their parents' plans gained coverage under Obamacare. Some of the demographic splits don't have anything to do with the health care law; they simply reflect that certain Americans (those who are higher income, for example) are more likely to have health coverage.

Still, further data in the Commonwealth study suggest that the health law is likely playing a role. Between November 2011 and March 2013, the Commonwealth Fund also saw a spike in awareness of the provision among young Republicans, a change that did not occur among their Democratic counterparts. At the same time that this demographic learned about the dependent coverage provision, they were also signing up at a higher rate.

For Sara Collins, a vice president at the Commonwealth Fund who lead the study, this explains why Republican enrollment in their parents' plans increased over the past 18 months while Democratic sign ups stayed stable.

"There wasn't much of a change in Democratic awareness," Collins says. "It went from 63 to 64 percent of registered Democrats who were aware. But if you look at awareness among young adults registered as Republicans it went from 62 percent in November 2011 to 74 percent in March 2013."

Collins said that much of the enrollment was driven by lower-income Republicans, who also became more aware of the dependent coverage option over the 18-month study.

The Commonwealth Fund study suggests that the partisan divide over Obamacare may not restrain who signs up. It certainly doesn't look to have impacted how young adults have used one of the law's earliest provisions.

At the same time, this by no means suggests enrolling young adults in Obamacare's other programs will be a slam dunk. Signing up for mom or dad's insurance plan simply meant adding a name to a pre-existing insurance policy. Buying coverage on the marketplace will mean paying a new monthly premium that could cost over $100.

While awareness of the dependent coverage option is pretty high - 62 percent of young adults said they knew about it during this survey in March - only 27 percent knew of the health law's new marketplaces. Awareness is lower among the uninsured and lower-income young adults.

"The young adults most likely to benefit are the least likely to be aware of them," Collins says. "These facts are concerning because young adults have one of the highest uninsured rates, and therefore stand to gain a lot."

If past is any prologue, the Commonwealth data suggests that Republicans could indeed come around to purchasing insurance on the new marketplaces. It's just unlikely to happen overnight, and will likely require an even greater awareness push.

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

Texas Gov. Rick Perry is seeking Obamacare cash. "Gov. Rick Perry wants to kill Obamacare dead, but Texas health officials are in talks with the Obama administration about accepting an estimated $100 million available through the health law to care for the elderly and disabled. Perry health aides are negotiating with the Obama administration on the terms of an optional Obamacare program that would allow Texas to claim stepped-up Medicaid funding for the care of people with disabilities." Kyle Cheney and Maggie Haberman in Politico. 

California farms are worried about Obamacare costs. "Insurance brokers and health providers familiar with California's $43.5 billion agricultural industry estimate that meeting the law's minimum health plan will cost about $1 per hour per employee worked in the field. The concern is felt from vineyards in Napa County to the almond orchards outside Coalinga, a Central Valley town best known for its state prison and mental hospital. Farm labor contractors generally rely on a 2 percent profit, and they say they will have to pass the added health care costs required by the new law on to growers." Sarah Varney in the New York Times.