Jim Geraghty speculates

[I]n 2008, Mitt Romney won 25.19 percent of the vote in the Iowa caucuses. A big question will be whether he surpasses that this year. In the past four polls in Iowa, Romney finished with 23 percent, 19 percent, 24 percent, and 23 percent. By many standards, the 2008 field of Republican competitors in Iowa was stronger than this one. …  A core element of Romney’s argument is that he is the most electable Republican in the field. But if he can’t surpass his previous threshold in Iowa – or perhaps another threshold of his 30,021 votes from last cycle – one will wonder why the most-electable Romney can’t beat his previous finish against weaker competition.