A national coalition of evangelical churches announced Tuesday that it is expanding a radio campaign aimed at persuading Republicans in Congress to support a broad overhaul of immigration laws.

The Evangelical Immigration Table launched a new round of ads in 56 congressional districts across 14 states, an effort that comes as Congress heads into the second half of its five-week summer recess. The ads, featuring local pastors, will be broadcast primarily on Christian radio stations over the next two weeks at a cost of $400,000, organizers said. They will air in Alabama, Arkansas, California, Colorado, Florida, Georgia, Illinois, Louisiana, Missouri, Oklahoma, North Carolina, South Carolina, Texas and Wisconsin.

The campaign builds on work the coalition has done over the past six months, during which members have held dozens of meetings with congressional offices. The coalition also had aired a previous round of immigration ads in five states during Congress's spring recess.

"The combination of this ad buy and our continued prayer for reform gatherings send one clear message: Evangelicals support action by the House of Representatives on immigration," said Barrett Duke, vice president of the Southern Baptist Ethics & Religious Liberty Commission.

Duke insisted the campaign has had an effect on the debate over immigration reform, even as House Republicans have continued to oppose a Senate-approved plan that features a broad path to citizenship for immigrants in the country illegally. The message from evangelicals, Duke said, is to provide political support to Republican lawmakers who might consider an immigration bill that includes citizenship provisions for many of the estimated 11 million undocumented immigrants.

"I don’t know whether it's a question of changing minds as much as it is giving more information to the congressmen, helping them to hear from a broader range of constituents than what was at one point a very loud, very small minority" opposed to citizenship, Duke said. Some GOP members have "become more nuanced in their expressions and statements" when talking about immigration reform.

Pastors involved in the campaign said that immigration is an important issue in their churches, with a growing number of members who are here illegally or have relatives who fear being deported.

"I have to deal with the collateral damage of our broken immigration system," pastor Felix Cabrera, of the Quail Springs Baptist Church in Oklahoma City, said on a conference call with reporters Tuesday. "Many are unjustly detained and deported. Many are separated from their families, leaving behind U.S.-born children without parents."