Editor’s Note: Joe Lockhart is a CNN political analyst. He was the White House press secretary from 1998-2000 in President Bill Clinton’s administration. He co-hosts the podcast “Words Matter.” The opinions expressed in this commentary are his own. View more opinion at CNN.

CNN  — 

Sometimes in politics the least surprising development can be the most important.

This is a true thing that has often been lost amid the reality show-style administration of our current President. While it was expected, Barack Obama’s endorsement Tuesday of Joe Biden is still critically important to the Democrat’s chances of winning back the White House.

Joe Lockhart

Let’s start with the raw politics. Former President Obama’s nod reinforces Biden’s existing strengths among the Democratic constituencies he needs to win the election, particularly black Americans. More importantly, Obama’s help on the campaign trail will motivate young people, many of whom have only recent memories of two presidents in their lives.

The contrast between those two – Donald Trump and Barack Obama is stark, not just on policy but on larger themes like goodness, virtue and purpose. Restoring those things to the White House would banish what Obama called in his endorsement video the “corruption, carelessness, self-dealing, disinformation, ignorance and just plain meanness” of the Trump tenure.

The praise for Biden from Bernie Sanders a day earlier was an additional overt clarion call to America’s youth – that this is their time to have their young voices heard at the ballot box. It was also practical and real help to Biden – framing his message as something that is progressive, that is bold and does call for structural change where needed. That is a critical narrative for Sanders and Warren voters to accept if Democrats are to succeed in turning them out in the fall.

It was more subtle perhaps, but the Obama endorsement also reminded Americans what it’s like to have an empathetic president who cares more about the American people than himself. His words of support for grieving and struggling families in this public health crisis were a salve for our many national wounds and stand in stark contrast to the selfish rants of the current President.

The former president, as the party’s senior statesman, can stay above the daily fray and remind people what it’s like to have someone decent, someone of high character, someone who has suffered the grief and struggles Americans are feeling now and someone who will always put the American people’s interest ahead of his own.

But perhaps, most important to Joe Biden, Barack Obama can make the case for a Biden presidency better than the former vice president can for himself. It’s no secret Joe Biden is not the best communicator that ever hit the campaign trail. He’s an old-school politician who excels at doing rather than telling.

Obama is able to make the case not only for electing his good friend, but for why government matters, why good government is important and why expertise and experience, devotion to both science and the rule of law, trumps the hunches of a former real estate developer, particularly in times of national crisis.

It’s somewhat reminiscent of the 2012 convention, while Obama was seeking a second term. The senior statesman of the party then, former President Bill Clinton, was able to make a powerful case for Obama that the president himself could not. That’s the kind of help Joe Biden can look forward to between now and election day.

Speaking of the value of others making the case, Bill Clinton’s convention address in Charlotte in 2012 was a great speech, but Michelle Obama’s was even better.

That is, the unspoken, but obvious bonus in Tuesday’s endorsement is that the endorsement of Michelle Obama comes with it. Her power and standing in the Democratic Party – and the world – is unrivaled. According to recent polls, Joe Biden holds an almost 2-to-1 advantage among women in America.

Hillary Clinton had similarly strong support. The difference is that Biden needs women to turn out in larger numbers in 2020 than in 2016. Michelle Obama is the single strongest weapon in the Democratic arsenal to make sure that happens.

Endorsements are almost always overrated in campaigns, as voters want the candidate to make their own case. But this one from Barack (and Michelle) Obama is critical to Joe Biden because the two can frame the stakes of the election and the personal qualities of Joe Biden in a way that is more compelling and effective than even Biden can himself.