From left, DC Circuit Judge Kentaji Brown Jackson, South Carolina US District Court Judge J. Michelle Childs, and California Supreme Court Justice Leondra Kruger
CNN  — 

It’s tempting to simply see the coming replacement of liberal Justice Stephen Breyer with a liberal appointed by President Joe Biden as a simple like-for-like replacement vote for what may be the permanent minority on the Supreme Court.

Don’t fall for that trap.

Supreme Court nominations ignite drama on Capitol Hill and excitement among partisan voters ahead of the midterm elections, and the eventual justice will impact US law for generations.

Here’s what you should know:

Making history

Biden will nominate the first Black woman to serve on the court. Justices serve for decades, so opportunities for historic turnovers that reflect the feel of society are rare. And any nominee could end up on the bench for decades.

The front-runners: Judge Ketanji Brown Jackson of the US Court of Appeals for the District of Columbia, California Supreme Court Justice Leondra Kruger and South Carolina US District Court Judge J. Michelle Childs.

RELATED: Another testy Supreme Court battle is the last thing America needs – but it’s probably what lies ahead

Changing dynamics on the bench

Justices bring their own perspectives and histories to the courtroom (even if all but one – Amy Coney Barrett – come from Ivy League schools). They’re more than faceless votes, even if the final results look that way. How they negotiate, how they craft their opinions, and simply how they get along together matter a great deal.

Behind the scenes at the court, Breyer has been known for trying to build consensus, even as the court grew more conservative. As CNN’s Joan Biskupic wrote: “The bespectacled Breyer, who often quotes British humorist P.G. Wodehouse and retells his grandchildren’s jokes, has conversed easily with all eight of his colleagues, dodging the friction of clashing ideologies and personalities.

“As such, Breyer will leave a hole in the fabric of the court when he officially steps down later this year. More than most of his colleagues, he worked to bridge the conservative-liberal divide that was long 5-4 and now is 6-3.”

Help for Biden and Democrats

The President has struggled this winter with a failure to get his Build Back Better spending plan through Congress or convince the Senate to change the filibuster rule to pass voting reform legislation.

This gives Biden a chance to have a legacy success – provided he can keep the 50 Democrats together.

REALATED: Breyer’s retirement gives Senate Democrats a chance to show their base they can deliver

All 50? What about Manchin and Sinema?

There’s always going to be moderate senators in either party who will need to be sold on a nominee. For Republicans, the focus during the Trump years was always on Sens. Susan Collins and Lisa Murkowski, for instance.

For Democrats, eyes immediately turn to Sens. Joe Manchin and Krysten Sinema, who’ve been responsible for much of Democrats’ woes on the legislative front of late.

But…Manchin and Sinema have backed all of Biden’s nominees for lower federal courts, CNN’s Tierney Sneed reports, so there are clearly areas where they’re more primed to stay together with their party.

In fact, Manchin told a West Virginia radio station Thursday he’s open supporting a Supreme Court nominee who’s more liberal than he is.

“It’s not going to change the makeup of the court,” Manchin said of a more liberal nominee. He said what’s more important is to ensure a nominee is “fair” and to gauge “the character of the person.”

“It’s not too hard to get more liberal than me,” Manchin added. “It would not bother me having a person who is sound in their thought person and who is sound in their disbursement of justice.”

Midterm madness

The type of dedicated base voter who participates in midterm elections are the ones who will pay the closest attention to the Supreme Court nomination.

Given that Democratic control of the House is hanging by a thread, and the Senate is currently 50-50, anything at all that excites voters is critical.

Liberals can breathe again

This should fire up the Democratic base, especially since there was an impatience with Breyer for not retiring last year.

Liberals still feel burned that Justice Ruth Bader Ginsburg didn’t retire when Barack Obama was President, and her death in September 2020 allowed Donald Trump and Republicans to change the nature of the court with the Barrett confirmation.

Since the Senate is 50-50, with Vice President Kamala Harris as the tie-breaker, Democrats not only can’t lose a vote, but their control of the majority and scheduling isn’t secure.

If a member dies – and there were recent health scares such as with Sen. Pat Leahy, a Vermont Democrat – there was a chance the GOP could suddenly control the Senate and block a vote, ala Merrick Garland in 2016. After all, you can’t win a vote that doesn’t happen.

Fires up the Republican base

The conservative base, already excited about the opportunity to take over Congress, will oppose any Biden nominee. But even if it’s a like-for-like vote, don’t expect the GOP to stay quiet.

The nominee will be a vehicle for Republicans to attack Biden’s liberal polices on a grander stage since more people will be paying attention. And Democrats confirming a younger liberal who could be on the court for 30 years will also remind GOP voters about how elections have consequences.

Yes, SCOTUS matters

The Supreme Court’s ruling in Roe v. Wade legalized abortion nationwide in 1973. This June, it’s expected the court will curtail, if not completely overturn, that decision.

The court in 2013 gutted the Voting Rights Act, leading to the current spate of new voting restrictions and political gerrymandering battles.

Justices this last decade also upheld Obamacare (three times) and recognized the right to same-sex marriages in a 5-4 vote.

So yes, every justice and every fight is critical.

CNN’s Manu Raju contributed to this report.