AP projections show Romney won 43 of 54 delegates available in the state, with 10 delegates going for Santorum. That final delegate available Tuesday hasn’t been awarded.
The results mean Romney now leads Santorum 563 delegates to 263 delegates. Romney is now almost exactly halfway to the 1,144 delegates he would need to clinch the nomination. He needs to win about 46 percent of the available delegates in the remaining two dozen contests.
Santorum, meanwhile, would have to win more than two-thirds of the remaining delegates to clinch the nomination, according to the projections.
His campaign set about arguing this week that it is actually much closer to catching up in the delegate race, owing to some strong performances in the ongoing delegate process in certain caucus states.
But that theory is based on many assumptions that cannot be verified or predicted at this point.
The delegates in Illinois were awarded by congressional district. In addition to his double-digit popular-vote loss, Santorum didn’t qualify for delegates in four of the state’s 18 congressional districts.
For more on the delegate race, be sure to check out the Post’s great GOP delegate tracker.