Guess the price was right.
It must have been agreed to before the debate where Pawlenty "lost" any chance to win, by backing off Romenycare (no one could have made such a misstep -- Pawlenty had to have decided to retreat, as "RomneyCare would naturally be put to him).
His little comeback a couple of days after the debate was "face-saving" and maybe to get reassurances of their deal before he assured them he would embrace Romney when called to.
If Romney can't stop (or slow) Perry in Florida, he will not be able to shake the "loser" label.