Healthcare latest: Protesters storm into Senate chanting 'kill the bill! don't kill us!' before crucial vote

Protests have erupted in the US Senate ahead of a planned procedural vote to consider a Republican healthcare bill that has been forged in secret and whose effects are largely unknown.

Capitol police quickly moved to close the halls around the public galleries, and were removing the protesters.

"Kill the bill! Don't kill us!" the protesters chanted in the Senate chambers, where the body of government known for deliberative and reasoned legislating resides.

The Senate later voted in favour of the motion to proceed to debate on the healthcare bill, with two Republicans defecting from the GOP to say no. Vice President Mike Pence cast the decisive vote to make the vote 51-50.

Republicans have promised for at seven years that they would repeal and replace the Affordable Care Act, an issue that became a defining opposition position during the presidency of Barack Obama. Critics have noted that the Republican Party's several failures to pass healthcare legislation in the House and Senate have illustrated that the Obamacare repeal promises were anchored more in rhetoric than actionable policy.

It isn't clear what the final product of any healthcare bills that may be considered may look like, but past proposals have generated some bad headlines. For instance, the House-passed bill was estimated to pose the risk of 23 million Americans losing insurance coverage over a decade. That estimation, determined by the Congressional Budget Office, gave fuel to even Republican senators like Susan Collins of Maine to knock the bill. Ms Collins and Republican Alaska Senator Lisa Murkowski joined Democrats in voting against the healthcare procedural effort.

It is uncertain if Republicans will be able to move forward following the procedural vote, and to forge together a healthcare bill that is palatable enough for moderate GOP senators to vote in favour of it.