WASHINGTON >> The Senate prepared for a key procedural vote during a rare Saturday session as Republicans race to pass President Donald Trump’s package of tax breaks, spending cuts and bolstered deportation funds by his July Fourth deadline.

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 $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,” said Senate Majority Leader John Thune, R-S.D.

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.

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.

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