I enjoyed this piece in the Washington Post today, which succinctly and accurately characterised the quite different strategies that Romney and Gingrich are adopting for attacking Obama, their choices based on whether they’re aiming at the Republican base (Newt) or the wider electorate (Mitt).
Romney is trying to reach a general-election audience, including many people who voted for Obama in 2008 and still like him personally. So he casts the president as an honest mistake, a low performer who simply needs to be replaced.
Gingrich, by contrast, is aiming at a Republican primary electorate that never liked Obama much to begin with. So he portrays the president as the representative of a whole poisoned way of thinking: an adversary who needs to be not just defeated, but repudiated.
These approaches also fit nicely with the respective candidates’ different styles: Romney appraising a failed job applicant, Gingrich crusading against a socialist evil. The obvious conclusion is that on the evidence of South Carolina the tougher Gingrich attack is the one which appeals the most to Republican primary voters, at the moment at least.