President Donald Trump launched an all-out charm offensive targeting opposition within his own Republican Party as he sought to secure the repeal and replacement of Obamacare.

In a critical early test of his ability to fulfill his campaign promises Mr Trump planned to head to various states and hold football stadium rallies as he seeks to overhaul President Barack Obama's controversial signature healthcare policy.

A bill to repeal the 2010 Affordable Care Act, known as Obamacare, cleared its first hurdle in Congress when it was passed by the House Ways and Means Committee at 4.17am following a marathon 18-hour session.

The House Energy and Commerce Committee also sat through the night as Democrats sought to delay passage of the bill with arcane procedural tactics.