President Donald Trump's choice for the Supreme Court has little margin for error in a narrowly divided Senate.
Brett Kavanaugh, whom Trump picked to fill Justice Anthony Kennedy's seat, will have a chance to shape a broad range of American policies for decades to come. First, a handful of swing-vote senators will get to decide whether Trump's nominee will even make it onto the top U.S. court.
A range of factors, including the possible justice's view on the Roe v. Wade ruling that legalized abortion and the political fortunes of red-state Senate Democrats, will determine the fate of Trump's choice in the Senate. After Republicans ended the filibuster for Supreme Court justices to confirm Justice Neil Gorsuch last year, nominees now only need a majority of 51 votes to get confirmed in the Senate.
The GOP holds 51 seats in the chamber, but only 50 Republicans will likely vote as Sen. John McCain, R-Ariz., fights brain cancer. If all Democrats unite in opposition to Trump's court pick, one GOP defection would sink the nomination. However, three vulnerable Democrats voted to confirm Gorsuch last year, and they could potentially take their cues from moderate Republicans once again.
Here are several of the key senators in the Supreme Court confirmation process:
Collins' decision on whether to confirm Kavanaugh could very well determine the action other senators take. He could potentially serve as a swing vote on whether to overturn Roe, and shape the future of abortion rights in the United States.
The Maine Republican has generally supported abortion rights and will look at a potential justice's views on the Roe ruling carefully.
"I would not support a nominee who demonstrated hostility to Roe v. Wade because that would mean to me that their judicial philosophy did not include a respect for established decisions, established law," Collins told CNN recently.
In a statement to NBC News on Monday night, the senator said Kavanaugh has "impressive credentials and extensive experience," but did not address abortion rights.
"I will conduct a careful, thorough vetting of the President’s nominee to the Supreme Court, as I have done with the five previous Supreme Court Justices whom I have considered," she said.
Murkowski, like Collins, has an independent streak in the Senate. Both senators, along with McCain, bucked their party last year to sink a GOP proposal to repeal and replace the Affordable Care Act.
The Alaska Republican has also generally backed abortion rights. She too will likely evaluate whether Trump's choice would overturn the Roe decision.
“My standards for Supreme Court nominees are extremely high. It is my longstanding practice to carefully scrutinize the qualifications of judicial nominees and to cast an independent vote when judicial nominations come before the Senate," Murkowski said when Kennedy announced his retirement.
Liberal groups will likely pressure both her and Collins to oppose whomever Trump nominates. Murkowski also voted to put Gorsuch on the Supreme Court.
Heitkamp runs for re-election this year in North Dakota, a state Trump won by more than 30 percentage points in 2016. In trying to keep her seat, the Democrat has emphasized that she has voted with the president's priorities a majority of the time.
That includes backing Gorsuch's confirmation last year. On Monday night, Heitkamp said she would "fully vet" Kavanaugh before making a decision.
"An exhaustive and fair process took place for Justice Gorsuch, who I supported, and it should and must take place again now," she said in a statement.
Late last month, Trump held a campaign rally in the state and claimed that Heitkamp would vote against whomever he nominated for the seat.
Manchin also faces a tough bid to keep his seat, running in a state Trump carried by more than 40 percentage points in 2016. The West Virginia Democrat voted to confirm Gorsuch last year.
Manchin has also given little indication of whether he will back the next nominee to the top court. In a statement Monday night, he said he will particularly focus on Kavanaugh's health care stance, in particular whether he would back the protections for insurance customers with pre-existing conditions enshrined into the Affordable Care Act.
“The Supreme Court will ultimately decide if nearly 800,000 West Virginians with pre-existing conditions will lose their healthcare. This decision will directly impact almost 40% of my state, so I’m very interested in his position on protecting West Virginians with pre-existing conditions," he said.
Donnelly faces a fight for his political life in November. Along with Heitkamp and Manchin, he was one of the three Democrats to support Gorsuch.
Trump won Donnelly's home state by nearly 20 percentage points. The senator also has given no clear indication of whether he will back the Supreme Court nominee.
On Monday night, he said he will "carefully review and consider" Kavanaugh's record and qualifications.
Jones was not yet in the Senate when it confirmed Gorsuch. As he won a special Senate election in deep-red Alabama in December, conservatives will certainly pressure him to support Trump's nominee. Jones has voted frequently with Trump's priorities.
"I will be diligent in measuring the record and in undertaking an independent review," Jones said on Monday night.
"Montanans have a lot on the line with this next Supreme Court Justice so I urge my colleagues on both sides of the aisle to put politics aside and do what’s best for this nation," Tester said in a statement Monday.
Pro-Trump super PAC America First Action is rolling out a seven-figure ad campaign that could target all of those senators, as well as Heitkamp, Manchin and Donnelly. Other conservative interest groups the Judicial Crisis Network and Americans for Prosperity are also targeting Democratic senators in red states with ad buys.