Updated 2:30 p.m. | Vice President Joseph R. Biden Jr. announced Wednesday he will not seek the Democratic nomination for president, immediately removing a major threat to former Secretary of State Hillary Rodham Clinton.

Biden, flanked by President Barack Obama and his wife, Jill, said he believed the window to do the many things to run for president “has closed.” Biden said he concluded that while he and his family were mourning his son Beau, who died in May.

While Biden will not be a candidate, he vowed “not [to] be silent” during the 2016 campaign.

He ticked off a list of policy items he said he will advocate for, saying Democratic candidates should “run on” Obama’s policies and legacies. And he dinged Clinton, the Democratic front-runner, saying Republicans are not Democrats’ enemies — though he did not name the former secretary of State, who called them such in the Democratic presidential debate last week.

Biden led off his remarks saying he always intended to make a decision after his family had concluded its collective mourning process. “The good news,” he said, is the family has done so, calling his son Beau, “our inspiration.”

“But we’re out of time,” Biden said.

All eyes have been on Biden for months, including Tuesday when he appeared at George Washington University with former Vice President Walter Mondale. Biden kept his presidential cards close, but touted his résumé — raising speculation he would run.

Biden, who lunched privately Tuesday with Obama, made clear he decided there was just not enough remaining time to raise the kinds of funds necessary to mount a credible bid or to organize a massive nationwide campaign staff and effort.

Political analysts and pundits had for months questioned whether Biden waited too long to make a decision. Modern presidential campaigns are expensive and require a massive nation-wide infrastructure, putting Biden at a huge disadvantage against the cash-rich and highly organized Clinton campaign machine — and even against that of Sen. Bernard Sanders, I-Vt.

In a statement, Clinton called Biden “a great vice president.”

“Like millions of others, I admire his devotion to family, his grace in grief, his grit and determination on behalf of the middle class, and his unyielding faith in America’s promise,” she said. “As vice president, Joe has been by President Obama’s side for every pivotal decision.”

She praised his role in bailing out the auto industry and helping to “pull our economy back from the brink of depression.” She also touted his work on raising wages and touched on his pledge to remain a national voice.

“And I am confident that history isn’t finished with Joe Biden. As he said today, there is more work to do,” Clinton said. “And if I know Joe, he will always be on the front-lines, always fighting for all of us.”

The vice president’s brief remarks included what seemed to amount to a campaign platform. The grandest vision he laid out was his desire to be the president when a cure for cancer, which took his son’s life, is found.

He talked about pushing policies that help America’s middle class, combating economic inequality, making a college education more affordable and tripling the child care tax credit.

Biden also indicated he would use the campaign season to advocate against what he called “a fundamental threat” to the country’s democratic system. He panned the existing system, saying moves are needed to “level the playing field” because “the wealthiest families control the process.”

On those and other issues, Biden vowed to “speak out forcefully” as the campaign moves forward on both “where we are as a party” and “where we need to go as a nation.”

Biden urged the Democratic candidates, without naming a single one, to use the Obama years as a basis of their campaigns. He said the U.S. is on the “cusp of resurgence,” saying he is “proud to have played a part in that.”

“This party will be making a tragic mistake if we move away from the Obama legacy,” Biden said sternly.

“There’s a lot that the president will have to get done,” he said of Obama’s final months. “But let me be clear that we will be building on a really solid foundation.”

Biden’s decision came a day after a poll showed more Democrats wanted him to sit out the 2016 contest than jump in.

In a statement, Sanders thanked Biden for “a lifetime of public service and for all that he has done for our nation.” He also said he looks forward to “continuing to work with” Biden to “address the major crises we face.”

Notably, Sanders pointed to many of the same issues Biden did in the Rose Garden.

“He understands the need to rebuild the middle class,” Sanders said of Biden, “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.”

House Democratic Caucus Chairman X avier Becerra of California told CQ Roll Call Wednesday morning there was no impatience among Biden’s party mates on Capitol Hill to make his decision.

“Making a decision to do something like run for president of the United States, it’s got to be ripe, it’s got to be ready to take out of the oven when you feel it’s ready to take out of the oven,” Becerra said. “Before then, you’ve got to make sure it’s baking the way you want it to. … In my book, Joe Biden has earned the right to make a decision when and if he wants.”

Democratic National Committee Chairwoman Rep. Debbie Wasserman Schultz of Florida trumpeted Biden’s work as vice president. But she did not repeat his call for the party’s presidential candidate to, as he put it, “run on” Obama’s tenure.

“While Vice President Biden will not be a candidate next year, his unwavering commitment to America’s working families is a legacy each of our candidates will proudly carry forward,” she said in a statement. “For the last seven years, Vice President Biden has served as one of President Obama’s closest advisers and played a critical role in advancing middle-class economics that brought our country back from a severe recession that was costing our economy 750,000 jobs a month.”

Wasserman Schultz acknowledged Biden’s promise to make his voice heard as the 2016 campaign goes on.

“Prior to joining the Obama ticket in 2008, Senator Biden was one of the Senate’s most respected voices,” the DNC chairman said. “His voice and support in the upcoming presidential election for whoever emerges as our nominee will be a powerful reminder of how much is at stake for hard working Americans.”

Biden sought the Democratic nomination twice before, once in 1987 and again 2007. His first campaign was derailed by allegations he had plagiarized parts of a speech and assignments in law school. During his second campaign, Biden dropped out after coming in fifth in the Iowa caucuses.

Obama selected him as his choice for running mate in the days leading up to the 2008 Democratic National Convention.  

Eli Yokley contributed to this report