Kerry's foreign policy gravitas makes him a natural to tout Obama's achievements on everything from ordering the successful hit on 9-11 mastermind Osama bin Laden a year ago to working to topple Libya's Moammar Gadhafi.
The long-serving Massachusetts lawmaker has been the chairman of the powerful Senate foreign relations committee for two years, replacing Joe Biden when he became Obama's vice-president.
But the buzz is building in his home state and beyond that there could be another reason for Kerry's starring role in Obama's re-election bid — he's a top candidate for secretary of state in a second Obama term if Hillary Clinton indeed makes good on her stated intention to vacate the post.
In a March 2011 interview, Clinton said she had no desire to keep the job if Obama wins re-election. She reiterated in January she would not remain at the State Department and, in fact, is finished with government after this presidential term.
"I have made it clear that I will certainly stay on until the president nominates someone and that transition can occur," said Clinton, who has been lauded for her stint in the job by Democrats and Republicans alike.
"But I think after 20 years, and it will be 20 years of being on the high wire of American politics and all of the challenges that come with that, it would be probably a good idea to just find out how tired I am."
That's prompted the type of wild speculation in the U.S. capital second only to the chatter about Mitt Romney's looming choice of running mate. Will it be Kerry? Susan Rice, the U.S. ambassador to the United Nations? What about Thomas Donilon, Obama's trusted national security adviser?
Kerry certainly seemed to be playing the part this weekend in Afghanistan as he met with President Hamid Karzai in Kabul.
The senator called a draft Afghan-U.S. strategic partnership agreement a "major success." The pact establishes U.S. support in Afghanistan for a decade after the withdrawal of combat troops.
In a recent interview with Politco.com, Kerry dismissed suggestions he has his eye on the State Department even though he was said to be disappointed when he was passed over for the job in favour of Clinton four years ago.
"People waste a lot of time playing games with speculation around here. I'm not going to engage in it," Kerry said when asked if he was interested in the most powerful cabinet post in U.S. government.
"I'm not thinking about it. I'm going to run for re-election (in 2014) and I'm very happy doing what I'm doing."
But not only has the 68-year-old senator been recruited by the Obama re-election team to herald the president's record on foreign policy and national security matters, but strategists also reportedly believe the well-heeled Massachusetts lawmaker is an effective foil to yet another monied politician from the same state — Mitt Romney, the Republican presidential front-runner.
Right down to their camera-ready shocks of salt-and-pepper hair, there's no shortage of similarities between Kerry and Romney: both are wealthy, enjoyed privileged upbringings, are Harvard-educated and possess often painfully awkward campaigning styles. Kerry had serious problems connecting with voters in 2004; so too does Romney in 2012.
It's clear the Obama campaign plans to play hardball on the president's foreign policy achievements, particularly the death of bin Laden. And the man who once chided Bush for failing to capture the notorious terrorist at Tora Bora right after the terrorist attacks of 2001 isn't likely to object.
"He took his eye off the ball, off of Osama bin Laden," Kerry said of Bush during a presidential debate shortly before the 2004 election.
In a new ad with former president Bill Clinton front and centre, the Obama campaign is suggesting that bin Laden might be alive today if Mitt Romney had been president last spring.
Romney was dismissive of that line of attack, saying Monday that he would certainly have ordered a similar hit in Obama's situation.
"Of course," he said in New Hampshire. "Even Jimmy Carter would have given that order."
Kerry, for his part, has begun to direct some barbs at Romney in recent weeks. He told the New York Times that Romney was playing into "Iranian hands" when he predicted Iran would get a nuclear weapon if Obama won a second term.
Romney, Kerry later added on the floor of the Senate, should play by the rules of "honest debate."
"He should be armed with facts instead of empty rhetoric," he said. "If we are to succeed ... in order to avoid a nuclear Iran, then at some point we must all act like statesmen, not candidates."