US President Barack Obama turns 50 tomorrow in the midst of the biggest challenge to hit his White House reign.
After signing off on the controversial debt deal, Obama is celebrating his birthday tonight in Chicago with a campaign fundraiser featuring jazz pianist Herbie Hancock and singer Jennifer Hudson.
After the concert, the President will attend a private dinner for a smaller group of 80 to 100 people before conducting a video conference with supporters at more than 1,100 organising meetings across the country.
On the day of his birthday tomorrow, Obama is scheduled to attend meetings at the White House.
Just as Bill Clinton marked a move to a new generation of American presidents, Obama and many of the Republicans competing for the White House in 2012 represent another shift in the age group to leaders who were children during the Vietnam War or the Civil Rights era.
Despite reaching his milestone birthday, Obama is likely to still be the youngest candidate in the field in the 2012 presidential campaign.
As he did in 2008, when national exit polls showed him winning 66pc of voters aged under 30, Obama probably will try to make his age an asset when he runs for re-election.
"For all of his youth, he's greyer and his wrinkles are deeper," said Bruce Buchanan, a presidential scholar at the University of Texas at Austin.
"Given the rigors of that job, youth can be an advantage."
Unless Texans Rick Perry or Ron Paul wins the Republican nomination, the 2012 campaign is likely to be the first modern presidential election in which neither major party candidate served in the military.
Perry (61) a governor still contemplating running, was an Air Force pilot, while Paul (75) a congressman in his third White House bid, was an Air Force flight surgeon.
Former Massachusetts Governor Mitt Romney, who leads in polls and fundraising among Republicans, is 64.
Among the potential Republican candidates who haven't announced, former Alaska Governor Sarah Palin would, at 47, be the youngest if she enters the campaign.
Clinton, who entered the White House a year younger than Obama, was the last president to turn 50 while in office.
He celebrated in August 1996 with a dinner at the Waldorf Astoria Hotel in New York, as well as a $10m (¤7m) gala at Radio City Music Hall to raise money for the Democratic National Committee and his re-election campaign.
Obama hasn't said much publicly about his birthday .
"I'm starting to think a little bit more about Medicare eligibility," he joked during a July 15 news conference in Washington, referencing the federal health insurance program for senior citizens.
Although he typically projects a stress-free demeanour, Obama has shown signs of age while in office as he deals with a US economy struggling to recover from the worst recession since the Great Depression.
Most obvious are the speckles of grey hair on his head.
A 2010 physical exam released by the White House showed the president had a resting pulse of 56.
He increasingly plays golf on weekends, instead of heading to the basketball court as he more commonly did during the 2008 campaign and during the early days of his presidency.