A desire by both men to secure their places in history might forge an unlikely pairing. BY RICK SANTORUM Obama also faces the reality of needing at least one Republican senator to join him to break filibusters. Many speculate that three moderate Republicans will provide the necessary Senate votes and the imprimatur of bipartisanship. . . . . . But I believe Obama has an ace in the hole among Senate Republicans. This unlikely ace can deliver not only the GOP moderates needed to break a filibuster, but also the stamp of bipartisanship: the 2008 GOP standard bearer, John McCain.....