Throughout Democratic presidential nominee Hillary Clinton's campaign, more left-leaning voters expressed concerns about some of the candidate's more moderate positions.

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But make no mistake, the stakes of the 2016 election for progressive causes are still high, especially when it comes to one key issue: Supreme Court appointments.

The results of this presidential election will determine the makeup of the Supreme Court, which will soon be deciding on a landmark case for LGBTQ rights. The new Supreme Court could also restrict gerrymandering, take soft money out of politics, and protect voting rights and the environment, thereby strengthening our democracy.

Since the death of Justice Antonin Scalia, the Senate has refused to endorse President Barack Obama's pick, Merrick Garland, resulting in a 4-4 split between liberal and conservative justices.

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Justice Ruth Bader Ginsburg is 83, and Justice Anthony Kennedy is 80. The next president is likely to nominate replacements for at least one of those justices as well.

At the third presidential debate, GOP nominee Donald Trump promised to appoint Supreme Court justices in the mold of Antonin Scalia, who opposed abortion rights. Trump also advocated increased gun access.

Clinton promised to pick justices who will protect women’s right to choose, will support marriage equality, and will overturn Citizens United.

Sen. John McCain, R-Ariz.; Sen. Ted Cruz, R-Texas; and Sen. Richard Burr, R-N.C., have promised to block all of Clinton's nominees. Burr recently told Republican supporters in North Carolina, "If Hillary becomes president, I am going to do everything I can do to make sure four years from now we still got an opening on the Supreme Court."

Only a Democratic majority in the Senate will thwart their plans for obstructionism. Thirty-four U.S. senators are up for re-election, and Democrats need to pick up four seats to tip the balance in their favor.

In the Congress, Democrats need to pick up 30 seats. For that to happen, Clinton would need to be ahead of Trump by 10 points.

Supreme Court cases to watch.

1. Transgender rights

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The Supreme Court is set to rule in February on its first transgender case. Gavin Grimm is suing his Virginia school district to use the boys’ bathroom, which corresponds with his gender identity. A victory for Grimm will mean a victory for LGBTQ rights.

"This is one of the most important days in the history of the transgender movement," Shannon Minter, the legal director of the National Center for Lesbian Rights, said. "The outcome of this case is likely to shape the future of that movement in ways that will resonate for a very long time."

2. Redistricting

Gerrymandering is one of the key reasons for legislative gridlock. Some states are fighting back.

In Arizona and California, voter-passed initiatives left the job of restricting to independent, nonpartisan commissions. When Arizona politicians lost the power to redistrict to their own advantage, they sued in federal court and lost. Had they prevailed, they would have succeeded in reducing Latino voters’ clout.

In 2015, the Supreme Court ruled 5-4 against those Arizona politicians, saying, "The core principle of republican government" is "that the voters should choose their representatives, not the other way around."

3. Money in politics

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Citizens United was decided based on a narrow 5-4 decision in 2010. To strike it down, a state needs to pass a restriction on campaign expenditures, which someone will then need to challenge in order for the Supreme Court to have another go at a ruling.

Unfortunately, conservative Indiana lawyer Jim Bopp, who crafted Citizens United v. Federal Elections Commission, is back on the beat. He is the lead lawyer in a series of lawsuits aimed at destroying political contribution limits.

Since super PACs can now raise unlimited amounts of money, thanks to the outcome of Citizens United, why not state legislatures? The Republican Party of Louisiana hopes to have access to unlimited funds of "soft money": unlimited contributions made by corporations, individuals, and labor unions to national political parties.

Replacing Scalia with a progressive justice will limit Bopp’s ability to further advance his cause. Bopp has long been active in the Republican Party.

4. Clean water, clean air, and action against climate change

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Just one more conservative justice could remove many of our nation’s waters from federal environmental protection under the Clean Water Act, while a new, more moderate justice could have the opposite effect.

The District of Columbia U.S. Circuit Court of Appeals heard arguments in September in a case challenging the EPA's Clean Power Plan, the first-ever federal limits on power plants' carbon pollution, which were designed to curb air pollution and pollution-related illnesses and to halt climate change. Regardless of the outcome in the appeals court, this case is likely to end up in the Supreme Court.

Donald Trump has said that climate change is a "hoax." He has also said he would eliminate the EPA, because "what they do is a disgrace."

As Tom Steyer and Michael Keegan wrote earlier this week in The Nation, "It’s hard to overstate the influence of the Supreme Court when it comes to safeguarding our health and our communities — from making sure Americans can access clean air and water, to regulating harmful pollutants that make our kids sick, to effectively addressing climate change once and for all."