Some time in the early eighties Rummy converts to Catholicism. When he makes what would in OTL be an unmemorable run for the GOP nomination in 1988 he instead bases his campaign around the RC pro-life movement.
Though he doesn't win, he boosts his reputation as the Catholic version of Pat Robertson in that primary season. In the lead-up to the convention the RR urges nominee Bush to choose Rumsfeld as his vice presidential running mate--Rumsfeld as a midwesterner and defence hawk and socon is the perfect choice. Bush/Rumsfeld is elected in November... Butterflies put in place in the decade up to then causes President George Herbert Walker Bush to suffer a massive stroke when he contracts stomach flu on a trip to Japan in 1991. Rest is history.