WASHINGTON — The White House budget director on Sunday said Republicans may need to "game the system" to get their tax plan through the Senate, while GOP Sen. Roy Blunt expressed confidence the legislation will be passed.

The Republican tax plan, which passed the House on Thursday, now faces major hurdles in the Senate partially stemming from a provision to repeal the individual mandate to purchase health insurance under the Affordable Care Act.

Blunt admitted on Sunday's "Meet The Press" that he isn’t sure whether that repeal will be included in what ultimately passes both chambers, saying, “it depends on where the votes are.” But he repeated his call to get rid of the mandate because “poor people pay that tax… it’s one of the many fallacies of Obamacare.”

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Director of the Office of Management and Budget Mick Mulvaney said on CNN Sunday that the Trump administration is open to dropping the mandate repeal if impedes passing the legislation.

Under the GOP tax plan, tax cuts for corporations would not have an expiration date, but the cuts for individuals expire after ten years – a fact Mulvaney admitted on Sunday was a “gimmick” to ensure the legislation adheres to the Senate’s strict rules that allow them to pass it with 50 votes instead of 60.

“In order to do that, the certain proposals can only have certain economic impact,” Mulvaney said on “Meet The Press.”

“One of the ways to game the system is to make things expire," Mulvaney said. "The Bush tax cuts back in early 2000 did the same thing. They supposedly would expire after nine years. What we tell folks is this is if it's good policy, it will become permanent. If it's bad policy, it will become temporary.”

"A lot of this is a gimmick. Obamacare was a gimmick to get through these rules in the Senate. And what you should really be looking at is the policies themselves. And we think these are excellent policies," Mulvaney added.

In the version of the bill passed by the House, the individual tax code will be reduced from seven brackets to four, with a top rate of 39.6 percent. Corporate taxes would be slashed from 35 percent to 20 percent. And the estate tax – which is for inheritances over $5.6 million for individuals – would eventually be ended.

An analysis provided to NBC News this week estimated that President Trump and his family could save more than $1 billion under the House bill.

Mulvaney said he couldn’t speak to the president’s taxes when asked about the analysis. “I think that was sort of litigated by the American public during the election,” he said, adding, "I will say this, listen, the president's going to pay much higher taxes on a lot of his properties, excuse me, because of because he has properties in high tax states.”

Tax reform remains one of the few major legislative accomplishments Republicans still have a shot at completing this year.

“It will pass the Senate,” Blunt assured.