A health-care mystery has pervaded Capitol Hill for weeks, one so big that three Democratic senatorial sleuths tried recently to solve it, piling into a taxi and snooping the Congressional Budget Office for clues.

Call it the Case of the Secret Health Bill, a caper designed to uncover a Republican plan crafted behind closed doors that would affect one-sixth of the U.S. economy.

The congressional trio behind Tuesday's scavenger hunt — Cory Booker, Chris Murphy and Brian Schatz — livestreamed their antics, leaving empty-handed. Still, their goofy political stunt made clear their objections to the hush-hush nature of deliberations to revamp America's health laws.

"We're United States senators. We're going to have a vote within days," Booker told followers via Facebook Live. "And we just don't have a copy of the bill."

Walking into the <a href="https://twitter.com/USCBO">@USCBO</a> now. <a href="https://twitter.com/hashtag/ShowUsTheBill?src=hash">#ShowUsTheBill</a> <a href="https://t.co/14VxBVhK2Q">pic.twitter.com/14VxBVhK2Q</a> —@SenBookerOffice

Congress will learn more on Thursday about the Senate's version of the bill when a "discussion draft," drawn up largely by an all-male working group of 13 senators, goes public. But to Democrats, and even some Republicans who grumbled about being kept in the dark during the legislative process, the pressure to vote before a July 4 deadline on the sweeping health-care changes carries the whiff of a rush job.

Alaska Republican Lisa Murkowski told Vox.com last week the lack of concrete information prevented her from sharing details with her constituents.

"This has been part of my frustration," she said. "What's the Senate bill going to look like? I don't know."

U.S. President Donald Trump has again branded Democrats as 'obstructionists' for not working with Republicans to reach a deal to replace what's commonly known as Obamacare. (Carlos Barria/Reuters)

According to the non-partisan Congressional Budget Office, the House version of the bill would leave 23 million more Americans uninsured in a decade.

One week may seem like a tight timeline for some fence-sitting senators to study and digest the bill before voting.

53 hearings for Obamacare

By tradition, the expectation in the Senate is that major pieces of complicated legislation would be subject to formal public debate early on, said Steve Billet, director of the Master's in Legislative Affairs at George Washington University.

The Republican proposal to repeal and replace the Affordable Care Act, also known as Obamacare, has so far advanced without the usual "mark-ups," amendments and committees.

Republican Senator Lisa Murkowski of Alaska is considered a swing vote on any Senate version of a health-care reform bill. (Becky Bohrer/Associated Press)

Democrats note that at least 53 hearings were convened over 2009–2010 during the Obamacare legislative process. Back then, Republicans accused Democrats of drafting the bill behind closed doors. With little approaching consensus on health care in America, "there should certainly be room for argument" this time, Billet said.

Instead, he believes the Republican party "has fashioned a piece of legislation that they can ram through" the Senate "with as little opposition as possible."

Thin majority

Critics believe that's precisely the point behind the closed-door strategy.

Not much ink has been devoted to the health-care bill, owing to ongoing Russia-related investigations involving the president, but also how little was known about the bill until now. The discussion draft circulating on Wednesday reportedly included a phase-out to the Medicaid expansion, elimination of funding for Planned Parenthood, as well as more latitude for some states to opt out of regulations.

Protesters rally last month during U.S. House voting on the American Health Care Act, on Capitol Hill in Washington. Republicans have faced division within their own party over how to repeal and replace Obamacare. (Yuri Gripas/Reuters)

Republicans have a thin 52-seat majority in the upper chamber, so losing the support of three Republicans could sink this bill if Democrats vote along party lines. Swing votes include Murkowski and Susan Collins of Maine.

Senate Majority Leader Mitch McConnell reportedly wants to bring a vote to the floor before the July 4 congressional recess, whether or not he has the 50 seats needed (plus a tiebreaker from Vice-President Mike Pence) to win passage under budget-related "reconciliation" rules. Doing so would help ensure health-care legislation doesn't clog up the legislative calendar so Republicans can focus in the fall on matters such as tax reform and the debt ceiling.

'A recipe for chaos'

It's to the Republicans' advantage to speed the vote through without giving Democrats time to drum up a public outcry, said Ilona Nickels, a former parliamentary adviser with the non-partisan Congressional Research Service.

"It's not about writing the perfect bill, but writing the bill that's possible," she said. "If McConnell were to try to figure it out in public, every lobbyist in town would be in the hallways of the Capitol. It would be a recipe for chaos."

Moderate Republican Senator Susan Collins said she and some of her fellow Republicans are worried the health bill they're supposed to vote on soon will shift billions of dollars of costs to state governments. (Jason Burles/CBC)

McConnell, known for his mastery of Senate rules, invoked Rule 14 to bypass the committee hearings. It's not an uncommon tool, but applying it to something as highly politicized as health-care reform raised eyebrows.

"Bills are routinely Rule 14'd every day," said Rachel Bovard, a former, longtime Senate staffer who served as a policy director at Washington's conservative-leaning Heritage Foundation think-tank.

Lack of transparency 'isn't a good trend'

Even so, Bovard points out that forsaking the principles of transparency and open process to avoid conflict "isn't a good trend," given that the legislative system is set up to allow for debate.

"These bills get cooked up in the back room, then brought out to members on the floor and they have to eat it all at once," she said. "Without opportunities for amendments …you remove the authority of the individual senators to fight for the ideas they were elected for."

An elderly patient receives treatment at an emergency room in Illinois. The House passed its version of the health bill before it had been evaluated by the non-partisan CBO. (Jim Young/Reuters)

Jon Gruber, who helped draft the original Obamacare bill, calls the secrecy shrouding the new health-care bill an "unprecedented" strategy, given the importance of the proposed revamp as a legislative "monster."

"This is a middle finger to democracy," Gruber said. "In a democracy, people are supposed to know what their representatives are voting for."

'It's going to be too late'

Although Gruber dismisses the hearings process as "political theatre," he worries about how quickly senators are being pressured to make intelligent decisions.

It's a concern shared by another Obamacare architect John McDonough, a public-health professor at Harvard University. "The window is closing so fast" before proper amendments can be made, he said.

"There's no real time for people's outrage to percolate. By the time the bill drops, it's going to be too late."

Last week, President Donald Trump reportedly told senators at a lunch he felt the House version of the bill was too "mean." A Congressional Budget Office score on the Senate bill is expected Monday before next week's expected vote.