As far as a Barack Obama-Hillary Clinton dream ticket is concerned, settling the scant policy differences would be a snap.
And their personal animus could be put aside easily enough. Ike held his nose for Nixon, JFK for LBJ and Kerry for Edwards. And vice versa. Politicians tend not to like each other much. Big deal.
The toughest challenge would be the very supposed strength and genius of such a partnership. That would be whether these two could really mess their conflicting appeal to such polarized groups.
First, the policy differences: There are but two moderately significant ones. Obama hasn't wanted to mandate health insurance, and Clinton has. She has advocated a summer moratorium on federal gasoline taxes, and he hasn't.
As inconveniences, those hardly measure up to the first George Bush's having called Ronald Reagan's ideas "voodoo economics."
What happens is that somebody takes back what he or she has said and turns the attention to the greater failing of the opposing party.
Obama could say that Hillary's vigorous advocacy of a health insurance mandate had, in fact, begun to persuade him. He could say he was now open to a mandate, and that, either way, the important thing was to draw a contrast between his and Hillary's shared commitment to universal care with John McCain's feeble, unworkable proposals.
Hillary could remind everyone that she advocated the gasoline tax moratorium only if offset by money from a new windfall profits tax. Since that wasn't going to pass, she could say Obama was right to argue that a gas tax moratorium alone and unreplenished was not the way.
The important thing, she could say, was to remind everyone that it was McCain who wanted to suspend the tax without replacing it.
Anyway, she could contend, the proposed moratorium was for the summer months, and thus will be moot as a general election issue in the fall.
The long-term problem of energy consumption and cost always was best addressed by green initiatives that she and Obama have long shared, she could say. Al Gore could be trotted out to help with that.
Now to the challenge: It was Bill Clinton, when he and Hillary presumed audaciously and a tad humorously to tout Obama as her running mate weeks ago, who pronounced that combining Hillary's appeal to rural voters with Obama's to urban voters would give the Democrats an unbeatable tandem. But that's not as easy as it sounds.
Her "rural" appeal is actually to white working-class people, many of whom may bear some racial or cultural aversion to Obama. That might not be overcome by Clinton's mere presence at the bottom of the ticket. Some of those votes for her were mischievous Republican cross-overs in the first place.
By any fourth November, the epic presidential choice inevitably comes down to the person at the top of the ticket, the one presuming to sit in the Oval Office.
Presidents are not elected by surrogates. A running mate's job is to do no harm and maybe help win one state.
That Hillary merely exists on the ticket might not make those vital Pennsylvanians and Ohioans any more receptive to Obama than Lloyd Bentsen made Michael Dukakis receptive to Texans.
She would do him no harm. She would help with energy and excitement, if with no particular swing state. She would frighten the Republican running mate in a debate. But he'll have to win it himself.
John Brummett, an award-winning columnist for the Arkansas News Bureau in Little Rock, is author of "High Wire," a book about Bill Clinton's first year as president. His e-mail address is jbrummett@ arkansasnews.com.