The 2012 presidential campaign played out on Twitter today with President Barack Obama and presumptive GOP nominee Mitt Romney exchanging tweets over the Lilly Ledbetter Fair Pay Act of 2009, which gives women greater power to sue their employers over pay discrimination.

Earlier today, Romney advisers said in a conference call that they were unsure of Romney’s position on the law.  That prompted the above attack-tweet from President Obama.

Romney tweeted this response:!/MittRomney/status/190120355598319618

Meanwhile, Romney spokeswoman Andrea Saul told Talking Points Memo: “He supports pay equity and is not looking to change current law.”

Philip Klein of the right-leaning American Spectator replied:!/philipaklein/status/190111668146159616!/philipaklein/status/190112146070319104

Which in turn led to this reply by left-leaning Talking Points Memo reporter Benjy Sarlin:!/BenjySarlin/status/190111994983100416

At the time it was passed, University of Chicago professor Ricahrd Epsein called the Fair Pay Act an Exhibit in “economic self-destruction“:

[T]he mere passage of this law will doubtless lead many employers to initiate expensive programs to reevaluate individual workers to head off the inevitable litigation–at the risk of inviting still more needless litigation… So understood, the Lily Ledbetter Fair Pay Act has nothing to do with fairness and everything to do with economic waste perpetrated in the name of social justice.