Image copyright Getty Images Image caption About $1 of every $5 in the US is spent on healthcare, according to federal government figures

US Democrats are up in arms about secretive Senate Republican efforts to repeal Obamacare, with no sign of a bill a week before a crunch vote.

President Donald Trump's party has been busily crafting a behind-closed-doors healthcare bill without holding any public hearings.

A Republican leader says he will present a draft bill on Thursday.

The legislation affects tens of millions of Americans and a fifth of the US economy.

Senators are writing their own version after their colleagues in the House of Representatives passed Obamacare repeal legislation six weeks ago.

Why are Democrats objecting?

Democrats say Republicans are keeping the legislation under wraps until the last minute so it can be rammed through with just a few hours of floor debate.

To highlight what they see as a lack of transparency, three Democratic senators on Tuesday filmed their failed effort to obtain a copy of the bill from the Congressional Budget Office.

Media playback is unsupported on your device Media caption Trump's battles with Obamacare - in his own words

On Monday, Democrats brought Senate business to a standstill with a five-hour "talk-a-thon" to express outrage at Republican tactics.

"Republicans are drafting this bill in secret because they're ashamed of it, plain and simple," said Senate Minority Leader Chuck Schumer.

Republicans accuse Democrats of obstructionism and argue that Obamacare needs to be replaced because it has failed to prevent premiums and other health costs from skyrocketing.

What's in the Senate bill?

Senate Majority Leader Mitch McConnell aims to have the legislation passed by 30 June, but few details have emerged.

He has said the party leadership will unveil a "discussion draft" of the bill on Thursday.

All that most lawmakers and the public have to work on is the House version. A non-partisan congressional review predicted that version would leave 23 million fewer people insured over the next decade.

The House bill would also cut some $800bn (£633bn) from Medicaid - a government health programme for the poor.

Media playback is unsupported on your device Media caption Healthcare battle in rural America

Is this legislative secrecy typical?

This clandestine approach to legislating has been seen in recent years, including the 2009 economic stimulus bill and the 2013 so-called fiscal cliff bill.

However, the upper chamber traditionally votes on major new legislation only after it has been crafted and revised by members of both parties.

When the Senate writes a bill, it usually circulates draft versions and holds public hearings for expert testimony before scheduling a vote.

The Senate healthcare bill is being crafted by one senator - Mitch McConnell, along with a coterie of aides.

How did it work with Obamacare?

Former President Barack Obama's 2010 Affordable Care Act was passed only after a year of public debate, including hundreds of hours of hearings on five separate committees.

A number of Republican amendments to Obamacare were incorporated by Democrats into the final bill.

Current Republican House Speaker Paul Ryan said in 2009: "If you rush this thing through before anybody even knows what it is, that's not good democracy."

Image copyright Getty Images Image caption An underserved community near Seattle received free healthcare from a charity

Mr McConnell said in 2010: "Democrats on Capitol Hill are working behind the scenes on a plan aimed at jamming this massive health spending bill through Congress against the clear wishes of an unsuspecting public."

Are any Republicans objecting?

The Republican leadership needs 50 votes to pass its health plan in the Senate. With a slender 52-48 majority, the party cannot afford many defections.

Kentucky Senator Rand Paul has already been critical of the plan.

"I think the death spiral of Obamacare continues," he said. "The Republican plan doesn't fix that; the Republican plan just subsidises it."

Asked whether he has seen the bill, Arizona Republican John McCain said on Tuesday: "No, nor have I met any American that has.

"I'm sure the Russians have been able to hack in and gotten most of it."

Senator Marco Rubio told CNN on Sunday: "If it is an effort to rush it from a small group of people, straight to the floor in an up or down vote, that would be a problem."