Giuliani added that he was "absolutely" sure that the GOP's stance on issues like abortion and contraception could open it to the risk of a rising third party.
"I'm concerned about how do we get back the Northeast as a voting bloc when we seem to be not modern enough on social [issues]," Giuliani said to CNN.
"I think the biggest problem right now, I think abortion you can work out … but I think the gay rights issue is a more current one right now. I think beyond all the religious and social parts, it makes the party look like it isn't a modern party, it doesn't understand the modern world we live in," Giuliani said.
Social controversies have dominated the past few weeks, with Republicans protesting a move by President Obama to mandate that employers provide insurance that would enable women free access to contraceptions. After religious employers protested, the president created an exception that would require insurance companies to provide the contraception coverage in those cases, although conservatives remain unhappy with the regulations.
Since then, Rick Santorum has made headlines on the campaign trail with a series of comments on social issues, including moments where he appeared to question the president's Christian faith, accused the president of encouraging abortion with mandates that provide for free prenatal tests that might identify genetic disorders and proposed stripping federal and state regulations on education.
Coupled with comments from leading donor Foster Friess about contraception, social issues have been dominant in recent GOP campaigning.