WASHINGTON - The Senate approved a budget bill early Friday that paves the way for passage of President Joe Biden's $1.9 trillion coronavirus relief package, with Vice President Kamala Harris casting the tie-breaking vote on the measure that will be key to enacting Biden's first major legislative initiative.

Passage of the budget bill came just after 5:30 a.m. Friday morning, after an all-night Senate session during which senators plowed through dozens of amendments in a chaotic process known as a "vote-a-rama." Democrats cheered the progress on measures to address the pandemic, while Republicans complained of partisanship and excessive spending.

The House, which approved its own budget bill on Wednesday, must now act on the Senate's version, which it is expected to do within a day.

With the budget resolution complete, Congress can turn in earnest to writing Biden's expansive pandemic relief proposal into law - and push it through the Senate without Republican votes if necessary under the special rules unlocked by the budget legislation. That process will take weeks, with Democrats eyeing mid-March as the deadline for final passage of the relief legislation because that is when enhanced unemployment benefits will expire if Congress doesn't act first.

"With the passage of this resolution we have the opportunity not only to address the pandemic, to address the economic collapse, to address the reality that millions of kids have seen their education disrupted," said Senate Budget Chairman Bernie Sanders, I-Vt. "We have the opportunity to give hope to the American people and restore faith in our government to fight for them."

Despite Biden's campaign promises of unity and bipartisanship, now that Democrats control both chambers of Congress and the White House they appeared ready to leave Republicans behind. Republican senators accused Democrats of hypocrisy and argued that, after already devoting $4 trillion to fighting the pandemic, including $900 billion in December, there was no need to spend another $2 trillion on what they termed a wish-list of liberal priorities.

"This is not the time for trillions more dollars to make perpetual lockdowns and economic decline a little more palatable," said Senate Minority Leader Mitch McConnell, R-Ky. "Notwithstanding the actual needs, notwithstanding all the talk about bipartisan unity, Democrats in Congress are plowing ahead. They're using this phony budget to set the table to ram through their $1.9 trillion rough draft."

The House passed the budget legislation on Wednesday, with all Republicans opposed.

Under the Senate's arcane rules, debate on the budget resolution in the Senate triggered a freewheeling amendment process known as a "vote-a-rama" that began Thursday afternoon and lasted for the next 15 hours, with some 45 amendments considered on a wide array of topics.

Republicans used the opportunity to force Democrats to vote on politically tricky issues, some with little connection to the coronavirus. Even if adopted, the amendments would not have the force of law - but they could show up in future political ads.

One of the first amendments offered, by Sen. Roy Blunt, R-Mo., sought to block funding for schools that have not reopened for in-person learning once teachers had been vaccinated. It failed on a party-line vote. An amendment by Sen. Pat Toomey, R-Pa., aimed at ensuring state and local jurisdictions cooperate with federal law enforcement authorities also failed on party lines. Democrats blocked an amendment by Sen. Tom Cotton, R-Ark., aimed at opposing packing the Supreme Court, and one from Sen. Bill Cassidy, R-La., that sought to block stimulus checks from going to inmates.

Two Democrats - Sens. Joe Manchin of West Virginia and Jon Tester of Montana - joined with Republicans to approve an amendment by Sen. Steve Daines, R-Mont., aimed at overturning Biden's move to block construction of the Keystone XL pipeline.

There was greater bipartisanship on display on other votes.

The Senate voted 99-to-1 to approve an amendment, led by Manchin and Susan Collins, R-Maine, to ensure that "upper-income taxpayers" do not receive stimulus payments. The measure did not define "upper income," although Democratic lawmakers are weighing how to target the checks.

The Senate voted unanimously in favor of an amendment by Sen. John Thune, R-S.D., aimed at providing tax relief to mobile health-care workers, and an amendment by Sen. John Barrasso, R-Wyo., to compensate schools losing tax revenue due to Biden's moratorium on oil and gas development on federal lands passed 98 to 2.

Sen. Todd Young, R-Ind., offered an amendment he said was aimed at ensuring that undocumented immigrants do not receive stimulus checks. It passed 58 to 42, with eight Democrats voting in favor.

Hours later, Sen. Joni Ernst, R-Iowa, sought to advance an amendment saying the federal minimum wage shouldn't be raised during a pandemic. To her apparent surprise, Sanders agreed with her, saying that his plan to raise the federal minimum wage to $15 an hour - which Biden has included in his relief proposal - phases in over five years and doesn't occur immediately. The Senate then adopted Ernst's amendment on a unanimous voice vote.

Despite the hours devoted to the amendment votes, the proceedings had a preordained conclusion: Senate passage of the budget resolution, which contains instructions to congressional committees to draft the actual relief bill.

Moving forward under the "budget reconciliation" process allows Biden's relief bill to pass the Senate with a simple-majority vote, instead of the 60 normally required. That will allow Democrats to move forward with no GOP votes if necessary, although Democrats and Biden officials insist that they hope Republicans will join them.

Biden's efforts to craft a bipartisan deal have been minimal, however. He met Monday evening with 10 Senate Republicans after they offered a $618 billion counterproposal, but the White House never indicated willingness to move off Biden's $1.9 trillion top-line or seriously consider a bipartisan compromise.

The group of 10 GOP senators, led by Collins, released a letter to Biden on Thursday thanking him for the meeting and praising some of his goals, but also raising "significant questions . . . about the size and scope of what is proposed" in light of the large sums already appropriated by Congress and tens of billions of dollars that remain unspent.

The few elements of Biden's proposal that Democrats are looking at scaling back - including who would qualify for a new round of $1,400 stimulus checks - appear designed more to keep their own party unified than to attract Republican votes. The Senate is split 50-50 between the two parties, with Democrats in the majority because Harris can break ties. So Democrats cannot lose a single vote if Republicans oppose them, giving moderate Democrats such as Manchin great influence in the process.

Republicans used the budget reconciliation process to pass their huge tax cut bill at the start of the Trump administration. The process has limitations, as certain provisions that don't have an impact on the federal budget can be struck from the legislation. Some lawmakers and outside experts say Biden's proposal to raise the federal minimum wage to $15 an hour could be at risk, for example.

In addition to raising the minimum wage and sending out a new round of stimulus checks, Biden's proposal would increase the child tax credit, extend enhanced unemployment benefits through September, provide rental assistance and money for nutrition programs, send $130 billion to schools to help them reopen, and allocate $160 billion for a national vaccination program, increased testing and other spending in the health-care sector.

The debate comes against a backdrop of continued high unemployment and a slower-than-desired vaccine rollout even as new variants of the coronavirus are discovered.

Signs of disunity were already emerging among Democrats. Members of the moderate-leaning Blue Dog Coalition caucus in the House released a letter Thursday to congressional Democratic leaders calling on them to move a stand-alone bill funding vaccine production and distribution before turning to the broader relief package. Biden has rejected the notion of breaking apart his relief package.