Washington, Jun 29 (AP) The Senate is taking a key procedural vote during a rare Saturday evening session as Republicans race to pass US President Donald Trump's package of tax breaks, spending cuts and bolstered deportation funds by his July 4 deadline.

But the tally was tight and voting came to a standstill as Vice-President J D Vance arrived at the Capitol to break a potential tie. Several Republican senators were registering their opposition to proceeding to open debate on the bill.

Republicans are using their majorities in Congress to push aside Democratic opposition, but they have run into a series of political and policy setbacks.

Not all GOP lawmakers are on board with proposals to reduce spending on Medicaid, food stamps and other programs as a way to help cover the cost of extending some USD 3.8 trillion in Trump tax breaks.

Ahead of the expected roll call, the White House released a statement of administrative policy saying it “strongly supports passage” of the bill that “implements critical aspects” of the president's agenda.

Trump himself was at his golf course in Virginia on Saturday with GOP senators posting about it on social media.

"It's time to get this legislation across the finish line," Senate Majority Leader John Thune said.

But as the day dragged, billionaire Elon Musk lashed out, calling the package “utterly insane and destructive.” “The latest Senate draft bill will destroy millions of jobs in America and cause immense strategic harm to our country!” the former top Trump aide said in a post.

The 940-page bill was released shortly before midnight Friday, and senators are expected to grind through the days ahead with hours of potentially all-night debate and countless amendments.

Senate passage could be days away, and the bill would need to return to the House for a final round of votes before it could reach the White House.

With the narrow Republican majorities in the House and Senate, leaders need almost every lawmaker on board in the face of essentially unified opposition from Democrats.

Senate Democratic leader Chuck Schumer said Republicans dropped the bill “in the dead of night” and are rushing to finish the bill before the public fully knows what's in it. He is expected to call for a full reading of the text in the Senate, which would take hours.

Make-or-break moment for GOP The weekend session could be a make-or-break moment for Trump's party, which has invested much of its political capital on his signature domestic policy plan.

Trump is pushing Congress to wrap it up, even as he sometimes gives mixed signals, allowing for more time.

At recent events at the White House, including Friday, Trump has admonished the “grandstanders” among GOP holdouts to fall in line.

The legislation is an ambitious but complicated series of GOP priorities. At its core, it would make permanent many of the tax breaks from Trump's first term that would otherwise expire by year's end if Congress fails to act, resulting in a potential tax increase on Americans.

The bill would add new breaks, including no taxes on tips, and commit USD 350 billion to national security, including for Trump's mass deportation agenda.

But the cutbacks to Medicaid, food stamps and green energy investments, which a top Democrat, Senator Ron Wyden of Oregon, said would be a “death sentence” for America's wind and solar industries, are also causing dissent within GOP ranks.

The Republicans are relying on the reductions to offset the lost tax revenues but some lawmakers say the cuts go too far, particularly for people receiving health care through Medicaid. Meanwhile, conservatives, worried about the nation's debt, are pushing for steeper cuts.

Senator Thom Tillis, who said he spoke with Trump late Friday explaining his concerns, announced Saturday that he cannot support the package as is, largely because of the changes to health care that he said would force his state to “make painful decisions like eliminating Medicaid coverage for hundreds of thousands.” Senator Rand Paul of Kentucky has been opposed to the bill's provision to raise the nation's debt limit by USD 5 trillion.

And GOP Senator Tim Sheehy of Montana said he would agree to proceeding only after being assured a provision for public lands sales he opposes would be taken out with an amendment.

After setbacks, Republicans revise some proposals The release of that draft had been delayed as the Senate parliamentarian reviewed the bill to ensure it complied with the chamber's strict “Byrd Rule", named for the late Senator Robert C. Byrd.

It largely bars policy matters from inclusion in budget bills unless a provision can get 60 votes to overcome objections. That would be a tall order in a Senate with a 53-47 GOP edge and Democrats unified against Trump's bill.

Republicans suffered a series of setbacks after several proposals, including shifting food stamp costs from the federal government to the states or gutting the funding structure of the Consumer Financial Protection Bureau, were deemed out of compliance with the rules.

But over the past days, Republicans have quickly revised those proposals and reinstated them. (AP) ARI