The US Republican Party on Monday unveiled a healthcare bill that it says will replace the Obamacare, or the Affordable Care Act, taking a step further in trashing what former president Barack Obama hoped would be his biggest legacy.

The bill, named the American Healthcare Act, was introduced by the House Committees of Ways and Means and Energy and Commerce. It will "deliver relief from Obamacare's taxes and mandates and lay the groundwork for a 21st century healthcare system," the GOP said on its website.

The proposed bill seeks to ax penalties levied on individuals and employers who don't purchase health plans, but instead encourages people to stay insured by allowing insurers to place a 30-percent surcharge on the premiums of those who are not continuously covered by health plans.

But the GOP has opted to keep two of the most popular features of the ACA, including letting young adults aged 26 or younger to stay on their parents' healthcare package and forbidding insurers to deny coverage to those with pre-existing conditions.