Lobbying groups opposed to the House’s healthcare reform bill are pinning their hopes on the Senate for big changes.

More than a dozen Democratic attorneys general on Thursday sought to intervene to defend a key part of the Obamacare healthcare law - subsidy payments to insurance companies - which is under threat in a court case.

House Republicans barely managed to pass their Obamacare repeal bill earlier this month, and they now face the possibility of having to vote again on their controversial health measure.

Blue Shield of California has the largest number of enrollees in the Covered California health insurance exchange, widening its lead over rivals Anthem Blue Cross and Kaiser Permanente, according to recently released data.

President Donald Trump's budget proposal to be presented Tuesday reflects the same $800 billion cut to Medicaid over a decade that was in the bill which last month passed the House. The Congressional Budget Office estimates that could lead to 10 million people losing healthcare insurance over 10 years.

Senate Republicans are showing early divisions over what to do about Obamacare's protections for people with pre-existing conditions.