The failure this week of a Senate Democrat attempt to curb the booming charter-school movement reveals battle lines within the majority party’s own ranks, say longtime education-policy advocates.

On one side are those who remain loyal to traditional Democrat interest groups like the Colorado Education Association, the state’s largest teacher union. On the other side are Democrats whose constituents have kids in some of the most troubled school systems in the state. Those Democrats increasingly find themselves allied with Republicans in support of wide-ranging education reforms, say education-policy insiders in both parties.

“As a Democrat, one of my main missions in life is to protect the downtrodden,” said a veteran lobbyist on education issues who asked not to be identified. “We’re supposed to protect the disfranchised as Democrats,” the lobbyist said, “and that forces members of our party to make a tough decision.”

Earlier this week, Republican senators banded together with key dissenting Democrats, including Senate President Pro-tem Peter Groff, of Denver, and Joint Budget Committee chief Abel Tapia, of Pueblo, to turn a Democrat bill that attacked charter schools into one that helps them. Assistant Senate Minority Leader This e-mail address is being protected from spam bots, you need JavaScript enabled to view it , R-Centennial, offered a succession of amendments to Senate Bill 61 that were embraced by the GOP as well as the Democrats who broke ranks.

That coalition has come together in previous legislative sessions to stem other Democrat attempts to roll back education reform on issues ranging from school accountability to educational choice. Those members are likely to unite on other bills this session.

The Democrat lobbyist cited a “transition” over the years by key Democrat stakeholders, like teachers unions, “away from being advocates for kids to being advocates for the system.” Those stakeholders are not addressing the concerns of the black and Hispanic communities, which are traditional Democrat constituencies, said political consultant and commentator Eric Sondermann.

“The Democratic Party has a fairly deep divide over educational choice,” said Sondermann, who has advocated for a number of school-choice and education-reform causes.

Lawmakers representing some of Colorado’s poorest inner-urban neighborhoods are

hearing from parents who feel their children are being let down by many neighborhood schools.

“The Democrats who break ranks (in the Capitol) are those who represent the kids who have not been well served by the system,” the lobbyist said.

Mark Hillman, former Republican Senate majority and minority leader, agreed: “It’s clear that in the last two to four years, a number of urban Democrats have realized the students they care about are not being well-served. They need more choices.”

Reform advocates say particularly blacks and Hispanics feel their children are being left out of the education equation, and they are making themselves heard.

“It’s been the minority community that has been willing to break with the Democrat caucus on these issues,” said Keith King, the Republican former House majority leader from Colorado Springs who has stumped for school choice for years.

“Some Denver Democrats have gotten to the place where they realize the school establishment is never going to meet the needs of children of color,” said King, who now runs an innovative charter program for teens. King said more and more Democrats are involved in the charter-school movement even though it was started in Colorado in the early 1990s by Republicans, including then-Sen. Bill Owens.

“You see the Peter Groffs, the (Denver Democrat Rep.) Terrance Carrolls willing to embrace options because they say, “These schools can deliver.’”