The former Pennsylvania senator won the state over former Mass. Gov. Mitt Romney in the March preference primary.
Romney is now virtually guaranteed the GOP nomination, allowing him and his party to focus energies on their effort to unseat President Obama.
“We made a decision to get into this race at our kitchen table, against all the odds, and we made a decision over the weekend that while this presidential race is over for me, and we will suspend our campaign effective today, we are not done fighting,” Santorum said during an address in Gettysburg, Pa.
The combination of his daughter’s recent sickness and poll numbers showing him possibly losing his home state primary apparently prompted the early departure.