In the 2008 Republican primary, Romney was Arizona Sen. John McCain's fiercest opponent, going neck and neck with the 2008 Republican nominee until just after Super Tuesday on Feb. 7, 2008.
Since his departure from presidential politics, not much has changed. He has kept his political action committee well-funded, perhaps the biggest statement that he is planning to run again in 2012. At 62, Romney's window of opportunity is closing, but not that quickly. He still has at least two campaigns left before it closes completely.
After delivering a speech at the annual Conservative Political Action Conference in February 2009, Romney won a straw poll of possible 2012 presidential candidates.
Although he has repeatedly shied away from committing himself to running for president in 2012 (he claims his efforts at writing a book are occupying most of his time), it is fairly certain that, barring some unforeseen circumstance, Romney will be a major player -- if not the candidate to beat -- in the 2012 Republican primary.