Conventional wisdom — particularly as articulated by Karl Rove and Ann Coulter — still says Mitt Romney is the most “electable” GOP presidential candidate. The MSM repeats that notion ad nauseum, too. After Rick Santorum won Mississippi and Alabama, for example, MSNBC.com ran an article with the headline, “Romney’s electability doesn’t help him break through.” The Washington Post’s Dan Balz wrote a piece headlined, “Rick Santorum hoping ideology will trump electability,” as though Rick Santorum lacks electability. Two examples among many.

But a Friday poll from Rasmussen Reports suggests Romney might be less electable and Santorum more so than Rove, Coulter and the MSM would have voters believe.

President Obama now trails former Pennsylvania Senator Rick Santorum by four points in a hypothetical 2012 matchup in combined polling of key swing states Florida, North Carolina, Ohio and Virginia. The president continues to hold a modest lead in those states.

Santorum leads the president 48% to 44% in the so-called Core Four states. Five percent (5%) prefer some other candidate in this matchup, and two percent (2%) are undecided. This marks a shift from last week, when the president was slightly ahead of Santorum.  (To see survey question wording, click here.)

Obama remains ahead of Romney 46% to 42%, showing no change from last week. Six percent (6%) prefer some other candidate in this matchup, and six percent (6%) are undecided.

Forbes’ Scott Harrington distills the argument against Romney’s electability and for Santorum’s competitive edge in a few brief bullet points:

• Along with entitlement spending in general, the central long-term issue confronting the electorate will be the Affordable Care Act — President Obama’s signature legislation — unless it is substantially overturned by the Supreme Court this summer.
• Because key features of the Affordable Care Act mimic the Massachusetts health care reform law championed by Governor Romney, his nomination would substantially neuter this central campaign issue.  He would be unable to effectively lever opposition to the health care law in media campaigns or in the Presidential debates.
• The President clearly wants to campaign against Wall Street and the “1 percent.”  Governor Romney would be an easy mark.   Senator Santorum would not.  It might be difficult to win an election with a campaign based on bogus allegations that Senator Santorum wants to prevent women from practicing contraception.

Harrington also notes that Romney still suffers from a robotic presentation of himself, while Santorum — with his passionate, un-tele-prompted speeches — has connected with voters on a gut level.

The Buckley Rule makes sense if you’re Nate Silver and an expert on electability. For the rest of us, it might make sense to just vote for the guy we’d really like to be president.