JOE BIDEN IS NOT RUNNING FOR PRESIDENT

Vice President Joe Biden is officially out of the 2016 presidential race.

In a speech from the White House Rose Garden on Wednesday, Biden declared that he would not seek the presidency, after months of public and private deliberations within his family about mounting a late challenge to former Secretary of State Hillary Clinton.

"As my family and I worked through the grieving process, I've said all along what I've said time and again to others, that it very well may be that the process, by the time that we get through it, closes the window on mounting a realistic campaign for president," Biden said in the Rose Garden, flanked by President Barack Obama and his wife, Dr. Jill Biden.

"I have concluded that it has closed."

Biden had been publicly flirting with the idea of running a third time for months, and speculation intensified over the summer as Clinton, the Democratic front-runner, stumbled.

Following the death of his late son, former Delaware Attorney General Beau Biden, earlier this year, Biden publicly mused whether he and his family were prepared for the rigors of a presidential campaign.

Biden said that though he would not be a candidate, he also would "not be silent." Much of his speech, in fact, sounded like a scrapped version of a campaign-launch announcement.

Biden cited, for example, campaign-finance reform as necessary to combat a "fundamental threat to our democracy."

"Because the middle class will never have a fighting chance in this country as long as it's just several hundred families, the wealthiest families, control the process," he said. "And I believe that we have to level the playing field for the American people."

Biden warned that the current political gridlock might be "more than this country can take" if it continued. He also added a final swipe at Clinton, repurposing a version of a line he used repeatedly over the past three days.

"I don't think that we should look at Republicans as our enemies," he said. "They are our opposition, not our enemies. Compromise is not a dirty word. I'm looking at it this way folks: How does this country function without consensus?"

Biden also spoke passionately about the need to find a cure for cancer. His son Beau died of brain cancer earlier this year, leaving his family distraught.

"I'm going to spend the next 15 months in this office pushing as hard as I can to accomplish this," he said. "If I could be anything, I would want to be the president that ended cancer. Because it's possible."

Biden in the weeks and months leading up to his decision had openly pondered whether he had the stamina to campaign in light of his son's death. In an emotional interview on "The Late Show" with Stephen Colbert earlier this year, Biden said he didn't know whether he would be able to pour his "whole heart," soul, energy, and passion into a run.

"I don't think any man or woman should run for president unless, number one, they know exactly why they would want to be president," Biden said. "And two, they can look at folks out there, and say I promise you have my whole heart, my whole soul, my energy, and my passion.

"And I'd be lying if I said that I knew I was there. I'm being completely honest. Nobody has a right in my view to seek that office unless they are willing to give it 110% of who they are."

But Biden had been running a quasi-campaign since August, when a Maureen Dowd column in The New York Times detailed the emotional details of how Beau Biden had urged his father to run.

In recent weeks, Biden and his close allies had been maneuvering behind the scenes to lay the groundwork for a campaign. Several Biden aides met with members of the Democratic National Committee to discuss state filing deadlines earlier this month. Former Sen. Ted Kaufman (D-Delaware), a top Biden political adviser, sent a letter to Biden loyalists last week detailing what kind of campaign the vice president would run.

"If he runs, he will run because of his burning conviction that we need to fundamentally change the balance in our economy and the political structure to restore the ability of the middle class to get ahead. And whether we can get a political consensus in America to get it done," Kaufman said.

"And what kind of campaign? An optimistic campaign. A campaign from the heart. A campaign consistent with his values, our values, and the values of the American people. And I think it's fair to say, knowing him as we all do, that it won't be a scripted affair - after all, it's Joe."

Biden would have faced significant electoral challenges.

Despite his name recognition, eight years as vice president, and decades in the US Senate, Biden would have gotten into the race significantly behind Clinton, who currently leads among Democratic primary voters in every national poll.

His poll disadvantage amplified over the past week, in the aftermath of the first Democratic presidential debate, and he sat significantly behind both Clinton and Sen. Bernie Sanders (I-Vermont), who has surged in the past few months.

"Joe Biden, a good friend, has made the decision that he feels is best for himself, his family and the country. I thank the vice president for a lifetime of public service and for all that he has done for our nation," Sanders said in a statement Wednesday.

"I look forward to continuing to work with him to address the major crises we face. He understands the need to rebuild the middle class; and to address income and wealth inequality, a corrupt campaign finance system, climate change, racial justice, immigration reform and the need for publicly-funded higher education."

Clinton also would have had a significant monetary advantage over the vice president, who would've needed to begin fundraising immediately to try and match the millions that Clinton has raised since becoming a candidate in April. Biden also would have needed to quickly build up his campaign infrastructure in early states, where Clinton and Sanders are both already established.