(@barackobama)Twitter erupted in excitement Friday as news broke that Mitt Romney had selected Wisconsin Rep. Paul Ryan as his running mate, but the volume promptly dropped off as bedtime arrived. Now, in the sober light of morning, the Obama campaign appears to be effectively mobilizing its opposition research on the microblogging platform.

At 9 a.m. EDT, conversation peaked, with Twitter users discussing Ryan at a clip of about 40,000 tweets an hour, according to social media analysis firm Attensity. By 11 a.m., four of the five top URLs in those tweets pointed to official Obama campaign material. Minutes after it was posted, thousands of people retweeted an @BarackObama tweet listing "5 Things you need to know about Mitt Romney's VP pick." Also in the top five were a press release from the Obama campaign calling Ryan the "architect of the radical Republican House budget," a landing page on the campaign website branding Romney and Ryan the "Go Back Team," and GoBackTeam.com, which redirects to

With anywhere from days to weeks remaining in the long and tortured period of speculation over Mitt Romney's running mate, the Signal is increasingly convinced that either Ohio Sen. Rob Portman or former Minnesota Gov. Tim Pawlenty will get the nod. The prediction markets currently give them a 35 percent and 16 percent chance of victory, respectively. In other words, there's better than a 1-2 chance that Romney will opt for the safest choices available.

You could be forgiven for needing a refresher on which of these two politicians is which. Portman and Pawlenty are both white males in their 50s with records as reliable conservatives, not firebrands. Either would provide Romney cover from the right while providing a sense of prudent sensibility to the rest of the country. These men both provide a moderate benefit, credibility with the right, with little potential cost.

Running mate odds

Sources: Betfair and Intrade

From a strategic standpoint, the biggest difference between them is that Portman is from

Many websites and publications are keeping score in the proxy presidential campaign being waged on Twitter. The Obama campaign account has 23 times as many followers as does the Mitt Romney campaign account, and @BarackObama tweets a dozen times for every one sent by @MittRomney. But no one is certain if these metrics have any relationship to electoral outcomes.

Elections may or may not imitate Twitter, but Twitter imitates life—with a marked liberal bent. Measures of sentiment on Twitter find users on the platform are reliably more positive on Obama than Romney compared with polls. When you drill into that data, however, you see a familiar pattern: The tweeting class likes Barack Obama as a person more than it likes him as a politician.

When Barack Obama turned 51 on Saturday, for example, Yahoo News' Twitter analysis engine picked up a tremendous surge in positive sentiment around the president. A tweet from the @BarackObama account wishing him a happy birthday and including a cute