Alex Salta says so, using fundraising, Facebook, and Twitter as metrics.
An important note is that Sarah Palin isn't included in the study, since she's not an announced candidate. Her Facebook presence dwarfs Romney's; she's at +3 million fans, while he barely tops a million.
As for Twitter, he's at 61,000 followers; she's roughly ten times higher -- at 614, 000. And it's safe to say that her Facebook notes and tweets have been far more influential than Romney's.
UPDATE: After I tweeted out that Palin was missing from the study, Romney spokesman, Eric Fehrnstrom, tweeted back:
No Ashton Kucher either.
Did he just compare Palin to Ashton Kutcher?