In Clinton's Veep search, 'Mr Boring' is right at the top

Senator Tim Kaine on Capitol Hill in Washington. Photo / AP

If Hillary Clinton had to pick her running mate today, I think she'd pick Senator Tim Kaine of Virginia.

Here's why.

The defining trait of Clinton's political career is caution. She doesn't ever leap before she looks - and looks and looks. Part of this is a function of the fact that Clinton doesn't have great natural political instincts - which she has repeatedly acknowledged during this campaign.

It's also the result of being enemy No. 1 (or, at worst, No. 2) for Republicans for most of the past two-plus decades. You'd probably be pretty wary of what you said and did if you had been at the centre of that storm since 1992.

Now, consider the state of the presidential race from Clinton's perspective. Her near-certain opponent Donald Trump is viewed unfavourably by 7 in 10 voters, had US$1.3 million in his campaign account at the end of May and continues to war with a not-insignificant bloc within his own party.

Clinton will never say this, but looking at those factors there has to be a belief within her campaign that if she simply blocks and tackles effectively in the next five months she will win. As a result, she will aim to do very little to fundamentally alter the race.

Combine Clinton's natural caution with the state of the 2016 race and all signs point to her settling on a vice-presidential pick who a) cannot possibly do any harm and b) is regarded as a governance pick - a person who has the résumé and knowledge to help Clinton run the decidedly complex federal bureaucracy.

That's Kaine - a former Mayor of Richmond, a former Virginia Governor, a former Democratic National Committee chairman and now a senator.

That he was a very early endorser of Clinton's 2016 campaign (he announced his support in May 2014!) and hails from a swing state doesn't hurt, either.

Kaine's big downside? He doesn't exactly light up the party base - or many others. "I am boring," he acknowledged in an interview with NBC's Chuck Todd on "Meet the Press".

I am boring

Senator Tim Kaine

Who else might Clinton pick? There has been quite a bit of reporting around this question of late; we know, for instance, that Clinton is vetting a shortlist that includes Kaine, Housing and Urban Development Secretary Julián Castro and Senator Elizabeth Warren. But her aides insist that Clinton's list of potential picks includes more than just those three.

Below is my attempt to rank the top five people by their likelihood of ending up as Clinton's running mate.

5 Amy Klobuchar

The senator from Minnesota gets the least attention as a VP pick of anyone on this list. That is probably deserving because she's a bit of a dark-horse pick. But if Clinton wants to pick or shortlist a woman - and doesn't want to pick or shortlist Warren - then Klobuchar makes sense. She has been an active surrogate for Clinton, has clear ambition beyond the Senate and hails from the Midwest, which will be the central battleground of this election.

4 Sherrod Brown

The senator's stock seems to be down somewhat in recent weeks - largely because picking the Ohio native would allow Republican Governor John Kasich to appoint Brown's successor in the Senate for the next two years. Brown remains appealing for his liberal credentials, his more protectionist view on trade and the fact that he represents an absolutely essential swing state. Perhaps most importantly, Brown is a stylistic contrast to Clinton - a sort of gruff-voiced everyman and a populist. That could serve as a nice complement to Clinton and round out the ticket.

3 Elizabeth Warren

I'm on record as being very sceptical that Clinton will wind up picking the senator. The two women don't have the best relationship - Warren was the last female Democratic senator to endorse Clinton, and she did it after the primaries were officially over - and Warren's hero status among liberals isn't really what Clinton needs right now. (Clinton's poll numbers among liberals have been quite strong.) But, as of today, Warren is one of three people we know that Clinton's VP search team is vetting. So I don't think she can rank any lower than third. My theory on why we know Warren is being vetted? A savvy strategy by the Clinton team to show liberals that they are taking Warren seriously - without any real negative consequences to floating her name.

2 Julián Castro

The former San Antonio Mayor was always going to be a member of the presumptive Democratic nominee's shortlist - and here he is. Castro is a less safe pick than Kaine - he's less proven on the national stage, he's younger, etc. - but his upside is also higher than Kaine's. Castro's speech at the 2012 Democratic National Convention was a giant hit and showcased his natural charisma and communication skills. Picking Castro would do two other things for Clinton: bridge the generational divide in the party (Castro is 41) and perhaps cement Hispanic voters as a reliable Democratic voting bloc for decades to come.

1 Tim Kaine

See above. Also, worth noting: Kaine had been vetted for the second-banana job by Barack Obama, adding to the sense of safety that picking him exudes.