The final Republican tax-reform bill unveiled Friday repeals ObamaCare's individual insurance mandate, leaving the GOP poised to blow a significant hole in the health-care law next week.

The change, which takes effect in 2019, removes one of the least popular parts of ObamaCare, but one that many experts warn is necessary to make the law function smoothly.

Without a mandate, there is less incentive for healthy people to enroll and balance out the costs of the sick. That is expected to lead to premium increases and could lead insurers to drop out of markets, potentially leaving some areas of the country with no coverage options.

Republicans say repeal of the mandate is a form of tax relief, because it lifts a penalty on people who decide not to buy coverage.

The Congressional Budget Office estimates that repealing the mandate will increase premiums by 10 percent and cause 13 million more people to be uninsured over a decade, but that markets would remain stable in "almost all" areas of the country.

Some experts say the impact of repealing the mandate has been overestimated, since it was never very effective to begin with, though repealing it would still have some effect.

Repeal of the mandate was already included in the Senate-passed version of the bill, and its inclusion in the final draft was expected.

The bill appears on track to pass both chambers next week.

Unlike broader efforts at ObamaCare repeal earlier this year, the repeal of the mandate has been largely free of controversy among congressional Republicans.

The main exception has been Sen. Susan Collins (R-Maine), who has pushed for passing two bipartisan ObamaCare bills before the end of the year in an effort to make up for the effects of mandate repeal.

It is unclear whether those bills can pass, given opposition among conservative House Republicans, who oppose the idea of making key payments to insurers known as cost sharing reductions.

Some experts also warn that the bills might not be enough to make up for mandate repeal. One of the bills, providing funding to bring down premiums known as reinsurance, could help make up for the premium rise from repealing the mandate, but some experts say more funding is needed.

In addition, there is the question of coverage loss and insurers leaving markets that the funding would not address as fully.