As Republicans planned to express their compassionate conservative side Tuesday at the Republican National Convention (search), some members of Congress spent the morning in the Bronx, paying tribute to students and teachers at a charter school in one of the poorest neighborhoods in town.

"We are both delighted and excited to be here," Rep. Mike Castle (search) of Delaware told a crowd at the school.

Castle is president of the Main Street Partnership (search), a coalition of moderate Republican members of Congress and their supporters that was on hand to help celebrate the opening of a new college resource facility for the Bronx Preparatory Charter School, which is now serving 350 minority students in grades five through 10 and expects to expand to 12th grade in 2010. The students are accepted to the school through a statewide lottery, but officials say all the students are currently from the Bronx.

The school was able to begin building the new facility with the help of a $150,000 donation from Sallie Mae Fund (search), a charity organization that provides financial aid for students and schools such as the Bronx charter institution.

Charter schools have flourished in the county over the last 10 years — currently more than 3,000 are in operation, said Jon Hage, president of Charter Schools USA (search), which runs 27 charter schools across the country.

Combining per-pupil state government funds and their own private fund-raising, charter schools have become a staple in the school choice movement, though debates continue over how effective they are in turning around failing students or how much they are taking away funds from regular private schools.

Republicans have often led the charge in support of charter schools, saying Democrats are too tied to teachers' unions that oppose the movement to back charter schools wholeheartedly. More recently, they say charter schools are yet another success story of President Bush's No Child Left Behind (search) education effort.

But Rep. Castle said charter schools are playing an enhancement role in the public education system.

"You're dealing here with children from difficult backgrounds who in certain schools might not be able to blossom — here they are given the opportunity to blossom," said Castle. "Republicans care about that a great deal."

Hage took it to another level. "There's rhetoric and there's action," he said. "We're actually going out and starting schools, in predominantly Democratic strongholds, for kids."

The Bronx school is being heralded by local leaders as a success. Joel Klein (search), chancellor of the New York City Department of Education, told the audience at Tuesday's tribute that the city was very proud of the work it has done for the students since its opening in 2000.

"Charters are no panacea," he said. "But charters can create the opportunity to really innovate and demonstrate excellence."

Just ask Hayley Estrella, 11, who said she loves Bronx Prep. "It's more challenging," she said. "I can do more work here than I did in public school."

But some educators argue otherwise. A recent study of charter schools by the American Federation of Teachers (search), one of the nation's largest teachers' unions, found that fourth- and eighth-grade students in charter schools often trail their public school counterparts in math and reading scores. Critics of the study say it only looked at a small group of handpicked schools and it did not give a full picture of how charter school students are faring across the country.

"Compared to any statistic citywide, Bronx Prep is doing very well," said Klein, who called New York the "most charter-friendly" place in the country.

Hage said Republicans need to emphasize charter success, especially now during a tough election in which undecided voters are looking for positive news on domestic issues like improving education. "This is an opportunity for Republicans to say, look, we're doing it every day," he said.