The most sweeping tax reform in decades in the U.S. was passed by the Senate early Saturday along the Republican party lines. However, the bill was met with great criticism by the Democrats who complained about last-minute changes and called the bill a “scam.”

According to the New York Times, the bill was passed with 51-49 votes along party lines with just one Republican, Sen. Bob Corker ( R-Tennessee), voting against it. The passage of the bill gives the Trump administration a much-needed victory on a major piece of legislation.

However, the historic bill still has a few hurdles to clear before it is signed into law by President Donald Trump, primarily because of the major differences between the Senate and the House versions, the latter of which was passed on Nov. 16.

Despite the passage of the bill in the Senate with amendments, the House and the Senate have to figure out a way to reconcile their differences over the reform. According to Vox, the negotiations are done in a joint conference committee, where Republicans from the House and Senate will get together to try to hash out a final plan.

Bloomberg states that the GOP while seeking a compromise in the negotiations, can’t afford to lose too many supporters. The Republicans can spare only 22 votes in the House and two in the Senate.

The major differences between the two bills, according to Bloomberg, include topics like temporary tax cuts, pass-through tax breaks, Obamacare individual mandate and alternative minimum tax.

Once a final plan is made based on the negotiations, both chambers of the Congress will have to pass it again. The White House and the Republican leaders want to pass a final bill by the end of the year and send it to Trump’s desk.

House Speaker Paul Ryan (R-Wisconsin) also tweeted after the Senate version of the legislation was passed and said he looked "forward to a conference committee so we can get a final bill to the president’s desk."

Reports said that just before the vote on the bill in the Senate on Friday, several other last-minute revisions were made to the bill, prompting an outcry from the Democrats. It was said that lawmakers received a re-written version of the legislation early Saturday morning and major changes were unveiled around 7 p.m. the previous day, following which the Democrats called the entire process rushed.

“I defy any member of the Senate to stand here and take an oath that they have read this and understand what in the world it means to businesses and families and individuals," Sen. Dick Durbin, (D-Illinois)., said, according to USA Today holding up what he said was a 479-page bill, Democrats had just received which seemed to include with hand-written changes.

The amendments, the report said, came with the motive to convince a number of Republicans to support the bill, including Susan Collins (R-Maine) and Ron Johnson (R-Wisconsin).

Following changes to the bill, Collins reportedly got a deduction for up to $10,000 in property taxes included in the bill, which otherwise did not include deductions for state and local taxes. Meanwhile, Sen. Jeff Flake (R-Arizona) said he had secured the change that provided for businesses to write off equipment purchases and a commitment that the Senate would move to protect undocumented immigrants who came to the U.S. as children from deportation.

Democrats slammed the last minute changes and took to Twitter to express their disappointment with the bill.

Trump has called for the final version of the tax bill to reach him by the end of the year, vowing to deliver a “big, beautiful Christmas present” to Americans. He said in a speech touting the legislation on Wednesday: “A vote to cut taxes is a vote to put America first again. We want to do that. We want to put America first again. It’s time to take care of our workers, to protect our communities, and to rebuild our great country."

Tweeting after the legislation was passed by the Senate, Trump said Saturday that we were one step closer to "MASSIVE tax cuts for working families across America." He also reiterated his desire of signing the bill before Christmas.