With a new move gaining steam to repeal and replace the Affordable Care Act, which is the federal health insurance law popularly known as Obamacare, President Donald Trump and members of Congress already are being urged to not go too far.

Trump is being urged by the U.S. Chamber of Commerce and organizations representing the health care and health insurance communities to preserve about $7 billion a year in subsidies for insurance purchased by some Americans.

It is probable several aspects of Obamacare will be part of whatever replacement the president and Congress devise. For example, ensuring young adults can stay on their parents’ health insurance policies until they reach 26 years of age has become very popular — regardless of whether it is an intelligent manipulation of the marketplace.

But pressure to retain entitlements in Obamacare was part of what doomed the effort to replace it just a few weeks ago. It is those very benefits that make the current system unsustainable. Many, if not most, of them need to be reconsidered.

Beginning work on “repeal and replace” with any preconceived notions amounts to opening a Pandora’s box that could kill the whole campaign.

Every aspect of Obamacare needs to be examined, not for its popularity, but to answer the question of whether it is sustainable.

Trump and congressional leaders should insist that on health insurance reform, everything needs to be on the table.