WASHINGTON (NewsNation) — The Supreme Court will weigh the constitutionality of President Joe Biden’s plan to erase billions of dollars in federal student loan debt on Tuesday.

The high court, with its 6-3 conservative majority, is hearing arguments in two challenges to the plan, which has so far been blocked by Republican-appointed judges on lower courts.

Arguments are scheduled to last two hours, but likely will go much longer. The public can listen in on the court’s website.

Biden’s plan would forgive up to $10,000 for borrowers who meet certain income thresholds and up to $20,000 for those who received Pell grants, impacting over 40 million Americans who took out student loans.

“This is a game changer for millions of Americans to get moving,” Biden said.

Twenty-six million people have applied and 16 million have been approved to have up to $20,000 in federal student loans forgiven, the Biden administration says.

The nonpartisan Congressional Budget Office estimated the plan will cost around $400 billion over the next three decades.

But major questions emerged over whether the president had the authority to implement this program.

“I’m confident the legal authority to carry that plan is there,” Biden said Monday, at an event to mark Black History Month.

While Biden and his team said the pandemic led to a national emergency and made it tough for borrowers to keep paying off expensive loans, opponents of the plan continue to raise legal questions, saying the president abused his authority.

“The president is not a king, and he has no power to dispense with the lawful acts of the legislature,” lawmakers wrote in a brief filed by more than 40 Republican senators.

Republican-led states and lawmakers in Congress, as well as conservative legal interests, are lined up against the plan as a clear violation of Biden’s executive authority. Democratic-led states and liberal interest groups are backing the Democratic administration in urging the court to allow the plan to take effect.

“It is incredible to think that the president of the United States can, with a stroke of a pen and no public input, no act of Congress, spend at least 400 billion dollars of our money,” Karen Harned, chief legal officer of Job Creators Network Foundation’s Legal Action Fund, said.

Biden’s team stood by the plan on Monday, highlighting how it could help people across the country.

“By doing this we give American families an opportunity to start a family, to buy a home. That’s how we’re seeing this plan,” White House press secretary Karine Jean-Pierre said.

The administration said a 2003 law, commonly known as the HEROES Act, allows the secretary of education to waive or modify the terms of federal student loans in connection with a national emergency. The law was primarily intended to keep service members from being worse off financially while they fought in wars in Afghanistan and Iraq.

In this case, Attorney and former federal prosecutor Mitchell Epner explained that the state of emergency here is the pandemic. His plan was a pandemic-era piece, or executive order, Epner said.

“The federal government has a pretty strong argument here because the law literally gives the discretion to waive or modify anything, including payments,” Epner said.

For now, the student loan forgiveness measure remains on hold as SCOTUS weighs what to do, leaving student borrowers wondering what could happen next.

Without it, loan defaults would dramatically increase when the pause on loan payments ends no later than this summer, the administration says. Payments were halted in 2020 as part of the response to the coronavirus pandemic.

“You don’t really know the expenses that you’re going to have, whether you’re going to have this monthly payment for student loans or not,” Frederick Bell, a University of Washington graduate, said.

In addition to the debate over the authority to forgive student debt, the court also will confront whether the states and two individuals whose challenge also is before the justices have the legal right, or standing, to sue.

Epner explained that this means the plaintiff will have to show that they are directly and materially affected by this law.

“Just because you don’t like it, you can’t go and sue,” Epner said.  “You have to show that some damage is either being done or threatened to be done to you. And the federal government has a very strong argument that none of these plaintiffs have standing.”

One of the fears that people who are looking at this case have is that if the states win, it could give the states the ability to sue to try to stop the federal government from doing what they want to do, Epner said.

“I mean, these are human beings who are aware of the human reality of this problem,” said Casey Mattox, the vice president of legal and judicial strategy at Americans for Prosperity. “But I think ultimately, these justices are going to be making a decision based on the law.”

While oral arguments will be heard today, a decision will take months to come down, likely around the end of June. Until then, student loans will remain paused. 

The Associated Press contributed to this report.