With the nomination of Brett Kavanaugh to join the Supreme Court, Nevada’s senior senator must decide whether to support a nominee who issued a pivotal decision on the state’s most explosive political issue: Building a national nuclear waste repository at Yucca Mountain.

In 2013, Kavanaugh was serving on the U.S. Court of Appeals for the District of Columbia Circuit. As part of a three-judge panel, he authored the majority ruling that stopped the Obama Administration’s Department of Energy (DOE) from killing the project and forced the Nuclear Regulatory Commission (NRC) to resume its licensing.

With the issue potentially coming before the Supreme Court as the state fights the project in the courts, the vote on Kavanaugh could be particularly thorny for Sen. Dean Heller, a Republican, who is facing a difficult path to re-election in November against Democratic Rep. Jacky Rosen in one of the nation’s most-watched races that could determine control of the Senate.

Heller, whose office, when asked, declined to comment on the opinion, has signaled his support for Kavanaugh, but also has said he would do anything to ensure the project does not get built. Supporting Kavanaugh could hurt Heller with Nevada voters—who in a January 2017 poll commissioned by The Nevada Independent found that 58 percent of those polled opposed the project. Opposing the nominee could also threaten his re-election by inviting the wrath of President Donald Trump, which would hurt Heller with the Republican base voters he needs to have a chance to win.

Democrats and outside analysts say that Yucca Mountain isn’t the most important issue in the Supreme Court fight. That status belongs to the Affordable Care Act and Roe v. Wade, which established a woman’s right to an abortion, two issues that Democrats say could also potentially end up before the Supreme Court. But in a race that is expected to leave Heller with little room for error, the injection of the Yucca Mountain fight is another complication for a candidate who doesn’t need it.

“Perhaps Rosen’s campaign will raise this as an issue,” said John Tuman, a political scientist at UNLV. He said that in response “Heller would say there are more issues here, even if he is going to be friendly on Yucca Mountain, I could still, as a senator, if you re-elect me stop Yucca Mountain. That would be my guess as to how he would try to spin it.”

Tuman’s comment was prescient. Heller’s spokesperson told The Washington Post that “The court clearly stated in its decision that it did not take a position on Yucca Mountain and simply ruled that the law must be followed if the project is funded by Congress.”

In a statement provided by her campaign, Rosen raised questions about Kavanaugh’s impartiality on Yucca.

“I have serious reservations about Judge Kavanaugh, and his pro-Yucca ruling adds to my list of concerns about how his confirmation to the Supreme Court would harm hardworking Nevadans,” Rosen said. “We have to do everything we can to keep our state from becoming the nation’s nuclear waste dump, and this ruling should raise major red flags for Senator Heller as he evaluates this nominee.”

In the Yucca case, Kavanaugh wrote the majority opinion, which argued that the NRC’s suspension of the licensing proceeding violated the Nuclear Waste Policy Act. First passed in 1982, the law initially directed DOE to site, construct and operate a geologic repository for high-level waste. The law was amended in 1987—known colloquially as the Screw Nevada Bill—and directed DOE to focus its work solely on Yucca Mountain.

Kavanaugh, who was joined by Judge A. Raymond Randolph on most of the decision, except a section on executive power, ruled that the NRC was under a legal obligation to continue the licensing process as long as left-over appropriated funds were available to do so.

“As things stand, therefore, the Commission is simply flouting the law,” Kavanaugh wrote, citing a provision in the law requiring the NRC to issue a final decision approving or disapproving the issuance of a construction authorization not later than the expiration of three years after the date of the submission of such application.

The dissenting opinion was written by Judge Merrick Garland, who had been Obama’s nominee to replace the late Antonin Scalia on the Supreme Court, but whose nomination was not considered by Senate Republicans, an unprecedented move. The judge called ordering the NRC to resume the licensing process “a useless thing.”

“In short, given the limited funds that remain available, issuing a writ of mandamus amounts to little more than ordering the Commission to spend part of those funds unpacking its boxes, and the remainder packing them up again,” Garland said. “This exercise will do nothing to safeguard the separation of powers, which my colleagues see as imperiled by the NRC’s conduct.”

By the time of the ruling, the three-year deadline had already passed. One significant reason for the delay on licensing was former Sen. Harry Reid, who fought to cut off funding for the plan. He also won over President Obama as an ally, who attempted to kill the project.

The DOE submitted its application to license Yucca to the NRC in 2008. But in March 2010, the Obama-run DOE had sought to withdraw the application. The NRC denied the request later in the year.

But during that time, Congress had reduced funding for the NRC's review of the application, with no funds appropriated beginning in fiscal year 2012. In Sept. 2011, the NRC suspended the adjudication of licensing Yucca. By the time of the 2013 ruling, the NRC had about $11 million, according to the ruling.

Heller is the example of why Senate Majority Leader Mitch McConnell urged Trump to choose a nominee without such a long history of opinions that could make Senate confirmation more difficult.

Whatever approach Heller takes, Yucca is one more headache stirred up by Trump’s decisions in a year that has been full of them. First, Heller was faced with an uproar over Trump’s pick of Ronny Jackson to lead the Veterans Affairs Department despite concerns over his qualifications. Heller got past that issue, important in a state with more than 200,000 veterans, when Jackson withdrew from consideration, only to be forced to answer for Trump on his rhetoric on immigration, including the forced separation of families at the border.

At a closed-door meeting in May, Heller reportedly asked Trump to hold off on one of his major campaign promises until after the election -- building a wall along the southern border. In June, Heller signed on to a letter asking Attorney General Jeff Sessions to halt the “zero tolerance” policy that forced the separation of migrant children from their parents at the border while Congress comes up with a solution.

Despite the chances of turning off the moderates and independents he also needs to win, Heller so far has embraced most of Trump’s policies and his nominees in a bid to keep the GOP base voters energized so they show up and cast their ballots for him on election day.

On the other side of the aisle, Catherine Cortez Masto, a Democrat, said that she remains undecided on Kavanaugh’s nomination, but is reviewing the judge’s record, including his ruling on Yucca.

“That’s a concern of mine,” she said of the Yucca decision, adding that she wants to sit down with Kavanaugh to discuss it along with his judicial philosophy, which she said, so far, has given her pause with regard to certain issues, including civil rights, access to health care, access to abortion and executive power.

“I’m also looking at some of the other opinions,” Cortez Masto said. “But most importantly, as I go through all of the research and look at his opinions and his writings and the things he’s done in the past, I want the opportunity to question him,” Cortez Masto said.

Supreme Court Justice Neil Gorsuch declined to meet with her during his confirmation process last year. She said she was never given a reason why Gorsuch did not meet with her and declined to speculate about why.