Mr Obama and Mr Romney both continually stress that they offer a very different vision of America's future.
Mr Obama and Mr Medvedev met during a nuclear summit in the South Korean capital Seoul.
Mr Obama and his wife, Michelle, attended ceremonies in New York, Pennsylvania and at the Pentagon.
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But, whether out of rage or calculation, Mr Obama and Mrs Clinton preferred to escalate.
Both Mr Obama and Mr McCain have already broken enough moulds without needing to break more.
Most polls suggest that voters agree with Mr Obama and the Democrats in principle.
It is all too easy to imagine Mr Obama and Mrs Clinton disagreeing messily.
Both Mr Obama and Mr Romney are keener on free trade than they let on.
Yet Mr Obama and his party seem a model of fiscal statesmanship compared with their Republican opponents.
Most still expect them to humiliate Mr Obama and possibly change the dynamics of this year's election.
With direct Israeli-Palestinian talks abandoned for now, Mr Obama and his team seem devoid of a strategy.
Both Mr Obama and Mrs Clinton sidestepped questions about whether she might run for the presidency in 2016.
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While both Mr Obama and Mr Boehner sounded consensual they were in fact restating their mutually exclusive positions.
Republicans retorted that, as a governor and former mayor, she has more executive experience than Mr Obama and Joe Biden combined.
Mr Obama and his Democratic colleagues on Capitol Hill are in grave danger of throwing away a rare chance.
Black men have been worse affected than whites, but their loyalty to Mr Obama and his party is unshakeable.
Mr Obama and his advisers will be wondering as they brace themselves for a bout of Middle East diplomacy.
For all their talents, both Mr Obama and Mrs Merkel are better at following public opinion than leading it.
Mr Obama and the Democrats have already lost some of the sheen they got from their electoral victory last year.
Both Mr Obama and his foes have produced fantastical budgets, full of illusory savings and ignoring the huge entitlement programmes.
But both Mr Obama and Mr Romney have waited until five months before the election to turn their attention to it.
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But reportedly, it was not informed that Mr Obama and Mr Wen had done a deal and were preparing to announce it.
For all the detail in their economic plans, Mr Obama and Mr McCain largely sidestep some of the most vexing economic problems.
Even that modest goal is now threatened by the creeping reluctance of Mr Obama and his allies to stick to their guns.
If there is any silver lining, it is the increased urgency with which Mr Obama and his Republican opponents have sought solutions.
It loudly booed when Mr McCain mentioned Mr Obama and Joe Biden.
My impression is that Mr Obama and Mr Cameron will be talking in some detail about the progress and direction of talks.
Mr Obama and his party do not, arguing that they suck money out of the public-school system and leave sink schools behind.
ECONOMIST: How will the candidates tackle schools and colleges?
Moreover, as Mr Chambliss notes, no bill will get anywhere without the agreement of Mr Obama and Republican leaders in the House.
In their more thoughtful moments, Mr Obama and Mr Romney admit that global competition is a reality that cannot be wished away.
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