Senate Majority Leader Harry Reid’s eight-year effort to keep a nuclear waste dump out of his home state of Nevada could soon become much more difficult.

Since 2007, Reid has used his powerful Senate position to block the federal government from moving more than 70,000 tons of high-level radioactive waste and spent nuclear fuel to Yucca Mountain, a federally designated nuclear waste repository located about 100 miles northwest of Las Vegas.

But polls indicate Republicans are poised to win control of the Senate in the November election. If the GOP prevails, Reid will lose not only his gavel but much of his authority to stop efforts to make Yucca Mountain the place to dump the nation’s nuclear waste.

“Harry Reid has had his finger in the dike,” one top Senate GOP aide told the Washington Examiner. “He’s been able to say he’s not going to take up any bill that considers Yucca Mountain as a nuclear storage facility. He won’t have that ability as minority leader.”

The federal government has spent two decades and $15 billion studying and preparing Yucca Mountain to store nuclear waste. The remote desert site was designated a potential nuclear waste dump in 1987 after Congress passed legislation requiring the Department of Energy to find one place to store nuclear waste being held at nuclear reactor sites across the country. DOE collected billions of dollars from energy consumers to help pay for development of the site.

But critics question the safety of the project. Hundreds of minor earthquakes have been detected in the area surrounding Yucca Mountain over the past 30 years, and some say storing nuclear waste at the site could result in groundwater contamination.

Nevadans remain overwhelmingly opposed to the project.

As minority leader, however, Reid would have far less power to influence federal policy on Yucca Mountain.

As majority leader, Reid was able to pressure President George W. Bush to appoint former Reid aide Gregory Jaczko to the Nuclear Regulatory Commission in 2005 in exchange for allowing votes on other Bush nominees.

President Obama tapped Jaczko to lead the commission four years later, and Jaczko promptly used his power to stall the Yucca Mountain project, in part by withholding safety reports. Jaczko also ordered DOE to halt its application for a construction license at Yucca Mountain.

Jaczko resigned from the NRC in 2012 and was replaced by Allison Macfarlane, who was handpicked by Reid and had long been critical of using Yucca Mountain to store nuclear waste.

But Macfarlane announced last week she is stepping down from the NRC, which leaves open the possibility a Republican Senate majority may be in charge of confirming the next nominee for the commission. And GOP lawmakers are unlikely to back a Democratic pick who transparently opposes the Yucca Mountain project as Jaczko and Macfarlane did.

If they win a Senate majority, Republican lawmakers are also likely to move forward with legislation that would advance the Yucca Mountain project.

In the House, where Republicans are likely to keep their majority, appropriators will continue providing money to the Energy Department to develop Yucca Mountain to store nuclear waste. In the Senate, a Republican majority may take up legislation, long opposed by Reid, to establish an independent agency to study both temporary and “permanent repositories” for the nation’s nuclear waste.

The author of the legislation is Sen. Lisa Murkowski, R-Alaska, who is in line to become chairwoman of the Senate Energy and Natural Resources Committee. Murkowski has resisted pressure from Reid to include a provision in the bill that excludes Yucca Mountain as a permanent storage site.

“It’s the most studied and expensive piece of ground in the United States,” Murkowski spokesman Robert Dillon told the Examiner. “She doesn’t believe we should be legislatively knocking it off the list. Let the science go forward and see what the determination is.”

The NRC just released the third installment of a Yucca Mountain safety evaluation and found that the project would meet the required human and environmental safety standards for a million years.

House Energy and Commerce Committee Chairman Fred Upton, R-Mich., called the report “game changing” and said it should add to the “bipartisan support” for the project in Congress.

Nevada political analyst Jon Ralston said Reid would make it very difficult for a Republican-led Congress to pass legislation that increases the likelihood Yucca Mountain will be used to store nuclear waste.

“He would use every parliamentary trick he has used since 1987 and some he has not even thought of yet,” Ralston said.