The conventional wisdom inside the Beltway is that Paul Ryan's presence on the Republican ticket is either going to work big for Mitt Romney or backfire completely. But there's another possibility that is perhaps even likelier: that it doesn't much matter at all. That's usually what happens with vice presidential picks. And it could be what happens with Ryan.

Paul Ryan is very controversial in Washington. Outside Washington? Not so much. In fact, he's not even very well known.

According to a Washington Post/ABC News poll, as of Aug. 10, 45 percent of the country had no opinion of Paul Ryan. They didn't love him. They didn't hate him. They just didn't know much about him. Now that the pick has been made, 29 percent don't have an opinion.

The Romney campaign agrees. In response to a USA Today/Gallup poll that showed Ryan polls worse than any vice presidential pick since Dan Quayle in 1988, Romney pollster Joe Newhouse said, "All these numbers indicate is the simple fact that Congressman Paul Ryan was not a nationally known figure prior to being named as Gov. Romney's vice-presidential pick."

Given those numbers, it's difficult to imagine that the post-Ryan bump will be radically different from what Romney would have received from any credible VP pick, and it might even be weaker.

The question, then, is what happens next  to break this race wide open in one direction or the other. And the answer might be...nothing. The Romney campaign isn't positioning Ryan as a Medicare-slashing radical. They're distancing themselves from the specifics of his budget, attacking President Obama's Medicare cuts and generally relying on Ryan's skills as a politician rather than on his ideas. That's an incremental strategy rather than a disruptive one, and we should expect it to register as such at the polls.

The Obama campaign is attacking Ryan as a Medicare-slashing radical. But they were going to attack Romney as that, as well. It's not clear that Ryan's presence on the ticket will make that attack radically more effective among the sort of low-information voters who aren't yet convinced by either side and don't really know who Ryan is.

Priorities USA, the Obama-affiliated Super PAC, argues otherwise. In a memo released today, Bill Burton writes:

Since Priorities USA Action began in mid-2011, we have focused extensive time on public opinion research surrounding the House Republican Budget authored by Representative Paul Ryan. Our research came to two main conclusions:

1.           The Ryan Budget is politically toxic document overall.  The specific proposals it contains – particularly on tax policy, education and Medicare – left voters viscerally angry.

2.           Our challenge would be to convince voters that a politician could support it.

This has been reported elsewhere. In focus groups, Priorities USA simply couldn't convince voters that anything about ending Medicare existed in the Ryan budget, and that, even if it did exist, Romney supported it.

"By choosing Paul Ryan," Burton argues, "Mitt Romney actually helped to solve one of the key strategic challenges we had in helping voters to understand that, in fact, Romney does support the kind of policies embedded in the Ryan budget."

Romney's choice of Ryan makes it clear that he supports the kinds of policies embedded in Ryan's budget. And it does make it easier to runs ads like, well, this one:

But that doesn't mean Priorities USA -- or the Obama campaign more generally -- will be able to convince undecided or Republican-leaning voters that the Ryan budget does what they say it does. Republicans, obviously, will be arguing the other side of that case, and they've got a lot of money. For every ad hammering the Ryan budget, there will be an ad trying to convince those same voters that Obama favors something equally awful, or perhaps even worse.

The base case with any vice presidential pick is that, if they do a good job, they don't do any harm. Ryan is so controversial in D.C. that many expect he'll have a significantly larger impact on the race. But he's not actually that controversial outside D.C., and his presence isn't leading either campaign to radically alter their strategy. So while I wouldn't go so far as to say that he won't have a significant impact on the campaign -- there's a reason the Obama camp has spent the last year trying to run against the Ryan budget -- there's a good chance that Ryan's impact proves much more muted than many political insiders are expecting. My hunch is the analysis right now is overly colored by the role Ryan plays in Washington, which is different than the role he's going to play in this race.

All that said, I do expect the polls to tighten in the coming weeks. Right now, Obama's poll numbers are unusually strong, and Romney is likely to get some bounce from both his VP pick and the Republican convention. The question is whether they're going to tighten significantly more or less than if Romney had picked, say, Rob Portman.