True, many of the seats were from the Northeast and Midwest, where the ideological gap can be manageable. But others, like Representative Heath Shuler of North Carolina, are outliers when compared to the average Democratic member. Now, Mr. Childers and Representative Don Cazayoux, a fellow newcomer from Louisiana, have the kind of conservative credentials that should put them to the right of the caucus. And there are potentially more such lawmakers to come in November if Democrats are as successful as they hope they are.

Republicans say the push to protect Democrats in red and purple districts has been a significant factor in the running fight between the two parties over House procedure as Democrats have been reluctant to open the floor to Republican proposals.

“I think their strategy both in 2006 and so far in 2008 has been a political strategy, not a governing strategy,” Representative Roy Blunt of Missouri, the No. 2 Republican in the House, said of Democrats. “You find candidates who can get elected in areas where they don’t agree with what the Democratic Party nationally wants to do. And then they get here and either can’t be a part of it or have to be put in such tight constraints that there can be no amendments offered on the floor by the other side.”

“That is part of why nothing happened last year that the majority said would happen,” Mr. Blunt said.

He was referring to the fact that in the 2006 campaign, Ms. Pelosi and her leadership team promised to treat the new Republican minority better than they had been treated by heavy handed Republican leaders during 12 years of minority exile.

But the fuller minority participation never materialized. And when Republicans were given a chance, they proved extremely adept at using procedural tactics votes to corner potentially vulnerable Democrats into embarrassing votes. So Democrats tightened the rules even more, sparking the fight on the Iraq spending bill that left Republicans howling they had been denied even the most basic involvement.

This intramural ideological divide is not a new problem for Congressional Democrats. Back in the days before the 1994 Republican revolution, Congressional Democrats were always split between the traditional liberal big-city wing of the party and Southern boll weevil Democrats who never met a defense project they didn’t like or a social reform initiative they did.