Former Virginia governor Timothy M. Kaine criticized the Obama administration’s new policy requiring some religious institutions to provide coverage for prescription contraceptives, a rare instance of disagreement between the Senate candidate and his close political ally.

The insurance rule has sparked fierce criticism from religious groups, particularly the Roman Catholic Church, which say the policy will require them to violate their beliefs.

Republicans have used the controversy to attack the White House, with House Speaker John A. Boehner (Ohio) vowing Wednesday that the new policy “will not stand.”

Kaine is the likely Democratic nominee in the contest to succeed retiring Sen. James Webb (D). Kaine was President Obama’s choice to lead the Democratic National Committee, and he has generally agreed with the administration on most policy issues. Former senator and governor George Allen, the front-runner for the Republican nomination for his former seat, has repeatedly sought to use that fact against Kaine.

But in an interview recorded Tuesday for the “HearSay with Cathy Lewis” program on WHRV-FM in Hampton Roads, Kaine made clear that he opposed forcing religious institutions to pay for birth control.

“I think the White House made a good decision in including a mandate for contraception coverage in the Affordable Care Act insurance policy, but I think they made a bad decision in not allowing a broad enough religious- employer exemption,” Kaine said, according to a transcript of his remarks provided by his campaign.

“This is something that’s been talked about a lot today, and I have definitely expressed my grave concerns to the White House about that. I support the contraception mandate, but there should be a religious-employer exemption that is broader than the one they proposed.”

Kaine, who is Catholic, has spoken frequently throughout his career about the importance of faith. He has cited it in discussing his opposition to the death penalty and his position on abortion. Kaine says he is personally opposed to abortion and has supported some restrictions, but he does not believe Roe v. Wade should be overturned.

Allen, meanwhile, is a strong critic of the Obama policy, saying last week that it was “an abhorrent overreach that violates the very liberty and religious freedom that our country was founded on.”

“By ruling that Catholic organizations will be mandated to provide services that are contrary to their religious beliefs, this action places practicing Catholics, who have a conflict of conscience, in a position where their job, education or health care will suffer,” Allen said.

In 1997, when Allen was governor, he signed a state law requiring insurance companies that provide prescription-drug coverage to offer plans that cover contraception. But private employers in the state are not required to buy such plans for their employees.