While aides say the commander in chief will argue in his final State of the Union address Tuesday that America's destiny depends on honoring progress made on his watch, he will be sketching a future in which he will play no major political role.

So his speech -- likely his last opportunity to grab an hour of uninterrupted prime time -- marks an important first step in a delicate and bittersweet yearlong process of handing over his legacy to the protective custody of his hoped-for successor, fellow Democrat Hillary Clinton

For sure, Obama has no intention of striding off the political stage just yet -- a factor that could complicate his relations with the Democratic front-runner in the coming months. He is making clear that with challenges including global warming, economic inequality and the still-open Guantanamo Bay prison, he will use every last ounce of authority and influence left to get things done.

"I want us to be able, when we walk out this door, to say, 'We couldn't think of anything else that we didn't try to do ... that we weren't timid or got tired or somehow thinking about the next thing because there is no next thing,' " he said in a pre-State of the Union video released on Monday.

But for all the promises of an engaged 2016, there's no getting around the fact that in just one year and eight days, Obama must cede the power to protect what he sees as his greatest achievements, including health care reform, staying out of Middle East quagmires and advancing social justice issues such as gay rights and economic prosperity.

There is no doubt that Obama has an awful lot riding on Clinton capturing the White House -- although he has also met with her left-wing rival, Vermont Sen. Bernie Sanders, the White House said Monday.

A Democratic successor is imperative for Obama because Republicans have vowed to dismantle key aspects of the Obama legacy immediately if they win back the presidential mansion after eight years, including Obamacare, a nuclear deal with Iran, executive actions shielding immigrants and policies designed to slow or reverse climate change.

Obama looks to Clinton

Though the White House says Obama will not endorse a candidate in the 2016 primary race, there is no doubt that he has long seen Clinton as the best hope for preserving his legacy.

In fact, that belief was one reason many people in the administration's inner circle were wary of a run by Vice President Joe Biden.

"I think Barack Obama believes that it is incredibly important that Hillary Cinton succeeds him," said a former close aide to Obama who is still connected with the White House. "The only way that we have an economy where people aren't losing their health care is if Hillary Clinton becomes president."

Jeff Shesol, who is familiar with the dynamic between a president and his preferred successor after working in the final years of the Clinton White House as a speechwriter, including on the State of the Union address, highlighted Obama's reliance on Clinton for his place in history.

"The single most important thing that could happen from here on out for the Obama legacy is the election of Hillary Clinton," he said.

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But the strength of the Sanders campaign, with polls showing a surge in the first two nominating states, Iowa and New Hampshire, threatens to upend the Democratic establishment's vision of a smooth passing of the party's torch from Obama to Clinton.

And Vice President Joe Biden, who decided against challenging Clinton for family reasons, fired a warning shot at the former secretary of state's campaign in an interview with CNN on Monday, saying Sanders was doing a "heck of a job" voicing the key election theme of inequality.

"Bernie is speaking to a yearning that is deep and real. And he has credibility on it," Biden said during an interview with CNN chief political analyst Gloria Borger.

"It's relatively new for Hillary to talk about that," Biden said, adding that while Clinton has come up with some thoughtful approaches on the issue, she had come to it later than Sanders.

Sanders, meanwhile, is adding to nervousness in Clinton's campaign by suggesting she is now in "serious trouble." Clinton has responded by arguing that only she has the global experience needed of a commander in chief in a dangerous world.

On one level, the fact that Obama hopes to entrust his legacy to Clinton is richly ironic. After all, a rejection of the kind of politics of "division and distraction" that he hinted that the Clintons helped sow was a strong thematic undercurrent of his 2008 election campaign.

But over the years, after working closely with Clinton when she was his secretary of state and as his prickly relationship with Bill Clinton eased during the former president's important embrace of his 2012 re-election campaign, it's been clear that Obama and his West Wing see the rival he slayed in 2008 as the best bet to safeguard his achievements.

Obama, for instance, was effusive in his praise of his outgoing secretary of state when she left office in 2013. He has continued to meet her for occasional private lunches at the White House and members of his orbit who once decried the Clintons now privately and publicly advocate for her.

For instance, David Plouffe, his one-time political guru who outmaneuvered the Clinton campaign in 2008, wrote in an eye-opening op-ed on Medium in October that she would make an "outstanding and worthy successor."

Does the President help the candidate?

The question for Clinton, as she faces a closer-than-expected race with Sanders and a potentially tight general election, is how much Obama helps her as she seeks to mobilize the Obama coalition of 2008 and 2012 but tries to mitigate the impact of his political failings.

The former secretary of state is touting the administration's record on the economy, with the halving of the unemployment rate and progress on gay rights, health care and climate change -- issues that are important to the Democratic base and the Obama hordes of young, affluent, educated white voters and minorities that she needs to turn out.

She is, meanwhile, vowing to go further than Obama on reforming the immigration system and to be more energetic on preventing gun violence.

But any downturn in the economy during his last year could render the President's record less impressive and harm her own chances.

Obama's struggles to impose U.S. power in the restive Middle East and elsewhere help fuel a Republican narrative that his foreign policy is a bust, to which she is vulnerable as his first-term secretary of state.

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Clinton has already signaled she would go further than Obama in Syria, in tackling ISIS, in mending relations with Israel and in adopting a tougher stance toward Iran, Russia and China than Obama has pursued. The Clinton campaign declined to comment on how Obama's foreign policy legacy will impact Clinton. But aides have previously quarreled with the Republican contention that her time as secretary of state will be a liability.

Clinton has also broken with Obama on the Trans-Pacific Partnership trade deal, which is opposed by many union leaders and grassroots Democrats. She backed the deal as secretary of state but now says does too little to protect the American worker.

Her move on TPP is one indication of why it is so hard for a candidate of the same party to succeed a two-term president -- a feat so rare that it's only been done once, by George H.W. Bush, since World War II.

Clinton has a firm interest in the incumbent President doing well, but she must also create a campaign in her own right that protects her from his baggage. It was a trick, for example, that Vice President Al Gore failed to pull off as he sought to succeed President Bill Clinton in 2000.

That's one reason Clinton has a clear interest in Obama's State of the Union address heralding a strong 2016 for the President.

Sources who know both Clinton and Obama say that the relationship between the President and Clinton remains friendly and cooperative. That will be tested, however, if Clinton is the nominee and as Obama faces pressure to recede into the background before the fall campaign. Awkwardness is bound to flair between the two camps, especially if Clinton finds herself obliged to begin criticizing aspects of his record for her own political reasons.

Tensions brewing

"I think there is tension inherently because you have a president who is still president who has certain points that he wants to press and certain directions he wants to lead and he wants his successor to go," said Shesol. "He probably has a good deal of confidence in his political judgment and thinks he knows best."

He continued, "There have been very few presidents who just wanted to get the hell out of there. President Obama doesn't want to stop being president. If we didn't have a 22nd Amendment, I am sure he would be running again."

The requirement for an incumbent president to step back -- a process that begins Tuesday night -- is not an easy one, and it requires him to bite his tongue in some situations when his preferred successor deems it necessary to criticize him.

For instance, in an interview with the Des Moines Editorial Board on Monday, the former New York senator said she would improve on Obama's tortured relationship with Congress.

"I have much more experience doing it. At the end of the day, you have to build those relations and consistently be looking for common ground," Clinton said.

But in the case of Obama and Clinton, the tension may be eased by the fact that there is now substantial cross-pollination between the two camps.

Two senior aides to the former first lady -- her communications director Jennifer Palmieri and the campaign's chairman John Podesta -- worked in the White House in recent years, and other lower-level staffers also have a foot in both camps.

And if there are strains in execution, they will pale in comparison with the common goals that Obama and Clinton share -- and which the President will lay out in Tuesday's prime-time address.