The Republican presidential candidate told GOP voters in Cincinnati on Tuesday that Obama has declared war on the Catholic Church. The administration recently issued a regulation requiring church-affiliated employers to cover birth control for their workers.
Some Catholics say the rule forces Catholic institutions to violate their religious convictions.
Romney also has criticized the Obama administration's actions, but Gingrich says Romney has a weak record on the issue.
Gingrich says Romney insisted that Catholic hospitals give out abortion pills against their religious beliefs when he was governor of Massachusetts.
In late 2005, Romney required all Massachusetts hospitals, including Catholic ones, to provide rape victims with emergency contraception.