Nate Silver inspects the candidate's fundraising efforts:

Unless Mr. Romney’s fund-raising pace picks up or he wraps up the nomination fairly quickly, he might need to consider self-financing, as he did in 2008. But that decision could carry some risk. Voters may be reluctant to contribute to a campaign once it looks like the candidate is willing to foot the bill himself, and such a decision could play into unfavorable narratives about Mr. Romney and his wealth.