Joe Biden won't run. Here's what that means for 2016.

The vice president signaled that he intended to play a role in the political life of the nation in the months ahead.

After months of speculation, the end came quickly. White House reporters had only a few minutes' notice that Vice President Joe Biden would make a statement in the Rose Garden on Wednesday with President Obama in attendance. It seemed unlikely VP Biden would announce a presidential campaign next to the White House itself with the incumbent by his side, and that proved to be case. Biden said that the window had closed for him and that he would not enter the 2016 contest.

“While I will not be a candidate, I will not be silent,” Biden said, indicating that he intended to play a role in the political life of the nation in the months ahead.

Biden then delivered remarks he might have prepared for an announcement speech, if he had run. Or perhaps it was his realization that this was his one chance to stand in the Rose Garden, near the seat of US power, and talk about the things that mattered to him most.

He said that the fate of the middle class needed to be at the center of Democratic Party efforts, though D.C. politicos sometimes deem “middle class” a synonym for “unsophisticated." Economic inequality threatens American democracy, Biden said.

The VP said that the nation might not be able to withstand four more years of bitter partisan warfare, and that Republicans were the opposition, not the enemy, as Hillary Clinton said in last week’s Democratic debate. He said Republicans and Democrats needed to learn to work together.

“We must change it,” he said of Washington’s political atmosphere.

Biden said he wished he could be the president who cured cancer. He indicated that he would make the fight against cancer a centerpiece of his efforts in his remaining time in office. His son Beau died of brain cancer earlier this year.

Many noted that with a few word changes Biden’s speech could have been an announcement speech, not a withdrawal notice. But Biden indicated that his grief over Beau, while diminishing, remained a real barrier to running.

“Beau is our inspiration,” Biden said. “Unfortunately, I believe we are out of time. The time necessary to mount a campaign for the nomination.”

Here are a few thoughts on the political aspects of Biden’s announcement:

He ran and lost. As a sitting vice president who had run for president twice before, Biden surely explored his options for running for the presidency. That’s a business that starts years before it surfaces in the public eye. His problem was that he lost this so-called “invisible primary” long ago. Ex-Secretary of State Clinton maneuvered to win endorsements and donors. She was the early consensus choice of party insiders, not him.

He's still the understudy. It’s quite possible that Biden has been wrestling with a candidacy in part to simply stay in the public eye, in case Clinton’s candidacy badly foundered. Right now, she seems to be weathering the controversy over her personal e-mail server and other problems, at least in terms of winning the nomination. But who knows what lies ahead? It’s also possible she could still develop serious political problems.

If that happens, Biden has done nothing to discourage the party from turning to him. He’s still their second choice for an emergency, as opposed to Bernie Sanders or Martin O’Malley.

“Biden out but he’s still the logical substitute if needed,” tweeted University of Virginia political scientist Larry Sabato after hearing the news.

The party unites. Biden went out of his way to subtly ding Clinton. He made a point of emphasizing that Republicans are not enemies, for instance. But by not running, he has ensured that Democrats will be able to present a united front early in the presidential campaign. His un-announcement shows the qualities that could make him a formidable Clinton surrogate campaigner: passion, an empathy with the little guy, and an apparent authenticity that Clinton cannot match.

Many Republicans had hoped for a Biden candidacy, in part because he has many genuine friends in the GOP ranks, in part because Republicans want Democrats to show internal dissension and disunity, too. That might still happen – Senator Sanders is running hard. But Biden won’t be the cause.