U.S. Sens. Joseph I. Lieberman and Susan Collins sternly told District officials Wednesday that Congress probably will cut funding for city schools if efforts to revive a federal voucher program for students are not successful this year.

At a hearing of the Senate Homeland Security and Governmental Affairs Committee, Lieberman (I-Conn.) and Collins (R-Maine) stressed that they and House Republicans are making the renewal of the D.C. Opportunity Scholarship Program a chief priority.

The senators issued their warnings to Mayor Vincent C. Gray (D) and Council Chairman Kwame R. Brown (D), whose testimony created a rare public split before Congress between a District mayor and council chairman.

Lieberman, head of the committee, said he and House Speaker John A. Boehner (R-Ohio) consider the voucher program, which allows students to use federal money to attend private schools, central to school reform efforts.

"I think the extra funds that come to D.C. . . . will be in serious jeopardy if the opportunity funding is not in this three-part program of public and charter schools," Lieberman said.

In 2004, a Republican-led Congress created the $14 million voucher program, which provides $7,500 annual vouchers to low-income families who want to send their children to private school. As part of the deal, Congress agreed to boost spending on city public and charter schools.

The program, long decried by teachers unions and some District officials as diverting resources from efforts to reform public schools, was essentially suspended by the Obama administration in 2009.

Although students enrolled in the program as of last year are allowed to keep their annual vouchers through graduation, no new students are being offered the federal support.

After efforts to restart the program failed last year on Capitol Hill, its supporters are sensing a growing opportunity now that Republicans again have a majority in the House.

Collins, the ranking Republican on the homeland security committee, echoed Lieberman in stressing that some funding for city schools could be scaled back if voucher supporters are not successful this year.

"I believe unless there is a three-sector approach, the money for D.C. public schools and D.C. charter schools will be in jeopardy," said Collins, who has teamed with Lieberman to sponsor legislation that would reopen the voucher program to new enrollees.

Efforts in the District to fend off congressional meddling could be complicated by Gray's and Brown's different stances on the issue.

Gray, who had appeared before congressional hearings as D.C. Council chairman, supported phasing out the vouchers. He has been an outspoken supporter of the city's popular charter schools, which are favored by many of the school-choice advocates who support vouchers. But Gray has long considered vouchers an improper congressional foray into local affairs, and he reiterated that opposition to Collins and Lieberman.

"My emphasis was, and continues to be, on building a solid public education system consisting of traditional public schools and charters," said Gray, who added that the District already has school choice because parents can choose to send their children to one of 52 charter schools.

But Brown, who was seated next to the mayor in the hearing room, broke with Gray by telling the committee that he recently embraced the calls for the D.C. Opportunity Scholarship Program to continue.

"The data suggests that students participating in the program are benefiting from the experience - academically and otherwise," Brown said. "I've heard it from families that they feel empowered and uplifted by expanded school choice."

After the hearing, Gray said he hadn't known that he and Brown would be offering opposing testimony.

Although he appeared rattled by the possible loss of some federal funding, Gray said he is digging in to resist efforts to allow the voucher program to reopen.

"It's a matter of expressing my views," he said. "But at the end of the day, we are going to do what's in the best interest of the children."