The death of Supreme Court Justice Antonin Scalia could be the biggest event to rock American politics in decades. With the passing of the most prominent conservative voice on the bench, all three branches of the federal government are up for grabs in 2016: the presidency; the Senate, which pledges to go to war over the nominee; and the Supreme Court, which might be permanently weighted either to the left or the right for decades as a result. Senate Majority Leader Mitch McConnell has already telegraphed that Republican lawmakers will do everything possible to block Barack Obama’s nominees, locking the G.O.P. into a virtual standoff with Democrats for the remainder of the president’s final term and forcing the clash over the Supreme Court center stage in the minds of already hyper-polarized voters.

Here’s what you need to know about the battle to replace Scalia and why it could be a game changer for the 2016 election.

Republican intransigence will help Democrats.

The decision by Republicans to declare war on the Obama administration over any Supreme Court nominee could be a huge gift to Democrats this election cycle. Not only did McConnell feed into the narrative that the Republican congress cannot get anything done—not even its most basic constitutional functions—he is also making an incredibly risky bet that the next president will be a Republican. The election of either Hillary Clinton or Bernie Sanders would almost certainly be treated as a mandate to nominate an even more liberal justice to the court. The heightened importance of securing the presidency could provoke a flight to more electable candidates on both sides, too, bolstering Clinton while prolonging the Republicans’ damaging intra-party slugfest between outsiders like Donald Trump and establishment choices like Jeb Bush. The possibility that the next Supreme Court justice could be nominated by a strict anti-abortion candidate like Marco Rubio, who has declared his opposition to abortion even in cases of rape or incest, will almost certainly galvanize the Democratic base.

President Obama could further mobilize voters by nominating a candidate who appeals to key Democratic constituencies, such as African-Americans or Hispanic voters. Or he could nominate a bipartisan candidate like D.C. Circuit Court judge Sri Srinivasan, a moderate who worked in the Bush administration and was unanimously confirmed by a 97-to-0 vote in 2013, forcing Republicans to explain why they would suddenly reverse course. Thirty-four Senate seats are up for grabs in November, including several races where vulnerable Republicans could face blowback for obstructing an appealing, nonpartisan nominee. “The fact is, when you elect a president, you have to assume a Supreme Court vacancy, he is going to make the nomination,” Senator Patrick Leahy, the ranking Democrat on the Judiciary Committee, said in a CNN interview Sunday. “If the Republican leadership refuses to even hold a hearing, I think that is going to guarantee they're going to lose control of the Senate.”

The Republican-led Senate could provoke a larger crisis.

Congress is already beset by unprecedented partisanship and gridlock. The last thing the deeply unpopular institution needs is for the upper chamber, whether controlled by Republicans or Democrats, to abandon their constitutional duty to provide “advice and consent” on Supreme Court nominees when it is politically expedient. As Senate Minority Leader Harry Reid argued in an op-ed Monday for The Washington Post, “If we enshrine this precedent and declare a functioning Supreme Court optional, subordinate to the whim of the Senate majority, it is easy to envision a future where the Supreme Court is routinely crippled.”