Mitt Romney is known to be a cautious and constitutionally conservative man.
Big personalities like New Jersey Governor Chris Christie – who is credibly rumoured to be the keynote speaker at the Republican Convention – are not his cup of tea.
High-profile trial balloons, like the much-ballyhooed "Condi Rice for VP" story leaked to the DrudgeReport website, were thinly-veiled attempts to change the conversation from Romney's refusal to release more than two years of tax returns.
Such a story also gives the appearance of commitment to diversity, but hours after the VP Condi story was floated, social conservatives attacked, reminding Romney that a pro-choice nominee like the former secretary of state would be DOA at the convention.
Other Republican rising stars like Louisiana Governor Bobby Jindal and Wisconsin Congressman Paul Ryan are more credibly being vetted, but contain risks rooted in policy specifics that delight conservatives but could ultimately alienate centrist swing voters.
So Romney seems likely to go for a VP-pick who will follow the doctor's mantra: first, do no harm. Conventional wisdom is settling on two top tier VP candidates: Ohio Senator Rob Portman and former Minnesota Governor Tim Pawlenty.
Portman has the advantage of hailing from a must-win swing state: Ohio. He is solid, steady and experienced with a background of government experience focused on economic issues – the core message on which Romney wants to campaign. But Portman has a two-fold downside. First, he was President George W.Bush's budget director - so if Romney picked him, he would be forced to account for the unpopular economic policies of the last Republican administration.
Second, Portman's extensive Washington experience includes a stint at a powerful lobbying law firm, some of whose clients were overseas - a combination that could compound Romney's problems connecting to middle class voters.
And so Pawlenty's stock is rising. He was considered a leading VP-possibility for John McCain in 2008, before the Arizona Senator chose Palin - and Pawlenty pursued his own (brief) presidential bid this time around before dropping out and endorsing Romney. So the two-term governor of a Democratic-leaning state has been thoroughly vetted.
Best of all, from the Romney campaign's perspective, Pawlenty's blue collar biography helpfully contrasts with their man's privileged background. He grew up poor - his father was a milk-man - and his rise confirms the endurance of the American Dream.
He is an evangelical, which comforts the social conservative base. And from the Team Romney perspective, the prospect of two Republican governors of normally Democrat states on the ticket sends a welcoming message to moderate voters.
Neither Portman nor Pawlenty are dynamic, charismatic figures. Their selection would show Romney playing it safe, for better or worse - offering voters the equivalent of a white bread sandwich.
As Sarah Palin showed, VP picks do matter. They are a nominee's first presidential level decision and offer enduring insight into their judgment.
Strong picks can balance out a candidate's political profile (remember Ronald Reagan's selection of the comparatively centrist George HW Bush) or help win an election by carrying their home state (as LBJ did for John F Kennedy by swinging Texas into the Democratic column in 1960).
Most of all, they matter because nine vice-presidents suddenly became president themselves, including greats like Theodore Roosevelt and Harry S Truman. What may seem like a "bucket of warm spit" can become a bully pulpit with the ability to make history, overnight.
John Avlon is senior columnist for Newsweek and The Daily Beast
