WASHINGTON (Reuters) -Republicans in the U.S. Congress scrambled on Thursday to resolve nettlesome tax and health care provisions in their sweeping tax-cut and spending bill on Thursday as President Donald Trump pressed them to pass it by a July 4 deadline.

Trump plans to promote the package -- which nonpartisan analysts say will add about $3 trillion to the federal government's $36.2 trillion in debt -- at an afternoon White House event that will feature truck drivers, firefighters, ranchers and other workers who the administration says would benefit from the bill.

But Senate Republicans have yet to produce their version of their legislation ahead of a possible weekend vote, and the overall shape of the bill appeared more uncertain after a nonpartisan referee ruled that several healthcare provisions violated the complex process Republicans are invoking to bypass Democratic opposition.

Those elements collectively represented more than $250 billion in health care cuts, according to Democratic Senator Ron Wyden of Oregon. Democrats have lined up against the bill, portraying it as a wasteful giveaway to the wealthiest Americans.

Senate Republicans have spent the last several weeks revising a bill that passed the House of Representatives by one vote last month. The nonpartisan Congressional Budget Office said the House version would add $2.8 trillion to the debt over the next decade, when factoring in its economic effects, and noted the toll would rise to $3.4 trillion when accounting for interest expenses,

It was unclear on Thursday whether Republicans could opt to rework the bill to comply with the complex budget rules, as they have already done with some elements, or seek to override the decision by the Senate parliamentarian. 

"It's pretty frustrating. But you know, what we've got to do is work through this process and come up with something that you know, fulfills the Trump agenda and also has fiscal sanity," Senator Rick Scott, a Florida Republican, told reporters. "Look, I believe this bill is going to pass. I know there's a lot of work left to do."

A source familiar with the situation said Senate Republicans still had a path forward and described the July 4 deadline as achievable.

The bill encompasses much of Trump's domestic agenda. It would extend his 2017 tax cuts, boost immigration enforcement, zero out green-energy incentives and tighten food and health safety-net programs. Nonpartisan analysts say the bill would effectively shift wealth from younger Americans to the elderly.

DEBT DEADLINE AHEAD

Trump has called on Republicans to pass the bill by the July 4 Independence Day holiday, but lawmakers face a far more significant deadline later this summer, when they need to raise their self-imposed debt ceiling or risk triggering a catastrophic default. 

Republicans who control both chambers of Congress broadly support the package, but they can afford to lose no more than three votes in either chamber. They remain at odds over several provisions -- notably a proposed tax break for state and local tax payments and a tax on health care providers that some states use to boost the federal government's contribution to the Medicaid health plan.

The bill would limit those "provider taxes," which nonpartisan watchdogs portray as an accounting trick that drives up Medicaid costs. Rural hospitals and other health providers warn that those cuts could force them to scale back operations or go out of business, and some Senate Republicans have sought to soften that provision.

The provider tax is one of several health and education provisions that has been ruled out of bounds by the Senate parliamentarian, creating further uncertainty about its status.

"This would be a chance to get it right and to protect rural hospitals," said Republican Senator Josh Hawley of Missouri, a critic of the provider-tax restrictions.

The parliamentarian also flagged provisions that would deny student aid and Medicaid health coverage to some immigrants, as well as a provision that would prohibit Medicaid funding for transgender medical care. 

Lawmakers a half-century ago decided that the Senate parliamentarian, currently Elizabeth MacDonough, would hold the power to determine what policies they can enact through "budget reconciliation," the process that Republicans are using now to bypass the chamber's "filibuster" rule that requires 60 of the 100 members to agree on most legislation.

Republican Senator Tommy Tuberville of Alabama wrote that she should be fired.

"Her job is not to push a woke agenda," Tuberville wrote on social media. Others, notably Senate Republican Leader John Thune, have said they will not to overturn her rulings.

(Writing by Andy Sullivan; Editing by Scott Malone, Franklin Paul and Alistair Bell)

By Bo Erickson, David Morgan and Andy Sullivan