House Republicans on Thursday sharply criticized a decision by the Department of Health and Human Services in September to deny a federal grant to a Catholic group that refuses to refer victims of human trafficking for abortion and contraceptive services, with some lawmakers saying that reflected an anti-Catholic bias in the Obama administration.

Democrats on the House Committee on Oversight and Government Reform countered that the Republicans were trying to “smear” the White House.

HHS officials testified that they acted appropriately in awarding the $4.5 million in funding to three other nonprofit groups even though reviewers had scored those applications below that of the U.S. Conference of Catholic Bishops.

The officials disputed the accusation of anti-Catholic bias, noting that in the days after denying the contract, the agency awarded the organization a separate $19 million grant. And they said the agency had provided more grant money to Catholic organizations during the Obama administration than in the final three years of the George W. Bush administration.

More than 30 Republican lawmakers have sent letters to HHS Secretary Kathleen Sebelius arguing that the decision to deny the grant was politically motivated and may have violated federal antidiscrimination laws. The group had been receiving the funding since 2006.

“If we are going to have a litmus test that ‘Catholics need not apply’ . . . we need to say so, we need to codify it in the law, and we need it to withstand the scrutiny of the Supreme Court,” said Rep. Darrell Issa (R-Calif.), chairman of the House oversight panel.

According to officials and documents, political appointees became involved in awarding the grant despite the recommendation from some career officials that the Catholic organization be funded. Issa argued Thursday that the potential for politics to determine who gets federal grants is the “more complicated issue.”

“We must ensure that the grant process can never be called an earmark process based on ideology or political appointees’ whims,” he said.

George Sheldon, acting assistant secretary for the department’s Administration for Children and Families, said the three groups that were awarded the grant money were “well regarded” and that officials made their decision based on the answer to this question: “Which organizations were best able to serve all the needs of the victims?”

“The unwillingness of the bishops to agree to provide the full array of services raised questions as to whether they could meet the full objectives,” he said.

Lawmakers grew heated as they argued over the Obama administration’s relationship with Catholics and with religious groups more broadly.

Rep. Christopher H. Smith (R-N.J.), a vocal opponent of abortion rights and author of the act that provided for the HHS grants, called the agency’s decision “an unconscionable abuse of power” and said there is now “clear proof” that the Obama administration will not consider the grant applications of Catholic groups through a fair and transparent process.

Rep. Gerald E. Connolly (D-Va.) argued that the “hyperbolic rhetoric” from some Republicans on the panel “would suggest that the purpose of the hearing is to try to smear the Obama administration.”

The American Civil Liberties Union, which had sued HHS over its previous awarding of the anti-trafficking grant to the bishops group, said in a statement Thursday that the hearing “was a political show-trial bought and paid for by the powerful lobbyists at the U.S. Conference of Catholic Bishops exerting their influence over certain members of Congress.”