Mitt Romney has a delegate lead that the competition is unlikely to overcome. Tuesday's elections marked the midway point of the Republican primaries. 

Romney has 658 delegates. Santorum has 281 delegates. Newt Gingrich has 135 delegates, and U.S. Rep. Ron Paul has 51. Romney likely will reach the needed 1,144 delegates on June 5 when five more states vote, including California and New Jersey.

While he hasn't declared victory, Romney has increased his focus on President Barack Obama. His speeches now include more points that seem meant to appeal to independens and Democrats.

"It isn't about one person or about even one party," Romney told a cheering crowd Thursday at his state headquarters in Harrisburg. "We're Republicans and Democrats in this campaign, but we're all connected with one destiny for America."

None of the other candidates have dropped out of the race. Ads supporting Santorum already have begun to run in North Carolina ahead of the state's May primary.