'The bill is removed from the reality of what the American people need,' says Senate Minority Leader Chuck Schumer.
After a series of amendments in a marathon session, some scribbled in the bill’s margins, the bill passed 51-49 in a nearly party-line vote, marking the largest tax overhaul in 31 years with nearly $1.5 trillion in cuts.
"Biggest Tax Bill and Tax Cuts in history just passed in the Senate. Now these great Republicans will be going for final passage," President Donald Trump said in a tweet, thanking the Senate Republicans for their support.
The House of Representatives approved a similar bill last week.
After the bill’s passage in both the U.S. House and Senate, the two chambers now need to sort out their differences and come up with final legislation before sending it to Trump’s desk for signing into law.
"Look forward to signing a final bill before Christmas!" the president added, expressing his long-desired tax reform to be finalized before the end of this year.
Along with all the Democrats, Bob Corker was the only Republican senator to cast a No vote, voicing fears the cuts in corporate taxes would hurt government revenues and push up the budget deficit.
"This is yet another tough vote. I am disappointed. I wanted to get to yes," Corker said before voting.
"But at the end of the day, I am not able to cast aside my fiscal concerns and vote for legislation that I believe, based on the information I currently have, could deepen the debt burden on future generations."
'Jammed through in the middle of the night'
The bill intends to lower the corporate tax rate in the country permanently and reduce the number of tax brackets.
The corporate tax rate is set to be lowered to 20 percent, from the existing 35 percent, in order to boost the earnings of American companies.
The number of tax brackets aims to be reduced from the current seven to four -- to 12 percent, 25 percent, 35 percent, and 39.6 percent.
Describing the bill as the Republicans' gift to the party's wealthy corporate backers at the expense of lower-income earners, Democrats sharply criticized Republicans for not giving members enough time to read the massive overhaul of the U.S. tax system.
The bill is "removed from the reality of what the American people need," said Senate Minority Leader Chuck Schumer.
However, Trump and his lawmakers have repeatedly claimed the bill is a boon to the middle class, despite several independent analyses that found it skewed toward corporations and the wealthy.
The nonpartisan Congressional Budget Office (CBO) said in a report that the proposed legislation would make lower-income Americans poorer, while giving massive tax cuts and benefits to the rich.
"I’m mad. And sad. We need to work together, compromise, and produce thoughtful results for frustrated families," tweeted Democratic Senator Claire McCaskill.
"Not a one-party-behind-closed-doors-no-time-to-debate-no-hearing-jam-it-through-in the-middle-of-the-night-mess."
McCaskill claimed that the bill had a "list of amendments" imposed by lobbyists, not senators.
"None of us have seen this list, but lobbyists have it. Need I say more? Disgusting. And we probably will not even be given time to read them," McCaskill tweeted before the vote, with a photo of a handed-out list of last-minute changes to the bill.