The United States Senate on Thursday approved a budget of $4 trillion for the 2018 fiscal year, paving the way for President Donald Trump's long-awaited tax code revamp.

The Republicans managed to push the budget through the Senate with a 51-49 vote despite opposition from ultra-conservative Republican senator Rand Paul.

Trump applauded the budget, a White House statement said, adding that the resolution will provide an impetus to the American economy through tax reform and tax cuts and simplify the over complicated tax code.

Along with the budget, the Republicans also approved an amendment to the Senate budget that aligned it to the already-approved House version of the bill, which included $622 billion for defense.

They also approved another amendment to pave the way for a future tax reform to be approved with a simple majority of 51 votes instead of the usual 60, which will help the Republicans, who have a narrow 52-seat majority in the Senate, to circumvent a Democratic opposition to the tax reform bill.

The keenness of the Republican Party, which controls both houses of Congress as well as the White House, to approve the tax reform as soon as possible prompted it to keep its deficit concerns aside and approve the budget.

In fact, some senators believe the vote on the budget was merely a mean to promote the tax reform, given that the 2018 fiscal year began 19 days ago and the Congress had already approved a budgetary proposal at the end of September to keep the government funded until Dec. 8.

Democrat Sen. Ron Wyden described the budget as "a right-wing fantasy document that paves the way for a hyper-partisan process on tax reform and trillions of dollars in handouts to big corporations and the wealthy."

However, Senate majority leader Mitch McConnell defended the tax reform saying it is "all about getting America going again and growing again," adding that it "represents a once-in-a-generation opportunity to replace a failing tax code."