Is Romney Underperforming?

Not really:

While Romney has not yet consolidated voters who do not approve of Obama’s performance, his failure to do so at this early stage is unsurprising. Even Obama, a popular candidate running in an exceptionally conducive political environment, did not reach 50 percent of the vote until October, and instead spent most of the summer mired in the mid-40s. With Obama's approval rating just short of 50 percent, and a decent number of voters sure to remain undecided in June, there is not very much room for a better GOP candidate to improve on Romney's current standing.