When several members of the Blue Dogs, a moderate-conservative Democratic faction, met last week with House Speaker Nancy Pelosi to negotiate the deal that allowed the health care bill to move to the floor, it was a signal of their rise to prominence.
The Blue Dog Coalition was formed after the 1994 election gave Republicans control of Congress. Democrats from rural and small-town districts, especially in the South and West, were worried that the party leadership, drawn mainly from big cities in the Midwest and Northeast, would present too liberal an image. So they drew together to try to protect themselves and, if possible, to increase their influence.
Their story is typical of the narratives behind the many other ideological, ethnic and geographical factions that have marked the history of Congress and are a feature today's House as well.
These organizations - essentially caucuses within each party - are relatively uncharted territory for students of Congress. But a pair of articles in the current issue of Congress and the Presidency, the journal published by the Center for Congressional and Presidential Studies at American University, examine the history and impact of these factions.
The Blue Dogs may be the best known at the moment, thanks to all the publicity they've received as controlling the "swing votes" on health care in the House Energy and Commerce Committee. But they are not the largest or necessarily the most influential such grouping.
Their 52 members are outnumbered by the 68 members of the New Democratic Coalition, a legacy of the Clinton years, and the 81 House members affiliated with the Progressive Caucus, which goes back to the early 1990s and has worked throughout its history for enactment of single-payer, Canadian-style health care legislation.
All of them are dwarfed by the Republican Study Committee, the largest and most conservative of the GOP factions with 106 members - more than half the entire Republican Conference.
It is not an accident that these factions are much more prominent in the working life of the House than of the Senate. The 100 senators are a small enough society that they can negotiate as individuals, which they are doing over health care legislation right now in the Finance Committee.
The House, with 435 members, is so large that individual backbenchers can almost feel lost. The factions give them a chance to mingle with like-minded legislators, to swap ideas and experiences, and figure out together how to accomplish their personal and legislative goals.
That is exactly what the Blue Dogs did in their negotiations with Pelosi and committee chairman Henry Waxman on the health care bill. They wanted - and got - protection for rural hospitals from Medicare cuts that the hospitals claim would be ruinous. They also tried to kill or weaken the proposal for a government-sponsored alternative to private health insurance, and had to settle for less than they sought.
There is nothing new about factions playing a central role in the legislative bargaining process. One of the articles, by Daniel DiSalvo of City College of New York, finds that factions, which he defines as "cohorts that are smaller and more agile than the party as a whole," have been prominent in Congress at least since the first years of the 20th century.
Often linked to interest groups, intellectual centers and activists outside Congress, they are "agenda-setting vehicles and engines of political change that develop new ideas, refine them into workable policies and promote them on Capitol Hill," DiSalvo says.
Historically, their greatest impact has been on the structure of Congress itself. The Democratic Study Group, a liberal faction whose numbers swelled after the 1974 election, led the way in strengthening the central leadership of their party in the House at the expense of autonomous committee chairmen.
Twenty years later, the Conservative Opportunity Society led by Newt Gingrich did the same thing on the Republican side. The result, for better or worse, is that today's House is a much more top-down, centralized body than it was during a long period of its history.
Some of today's factions welcome that trend. Others, including the Blue Dogs, do not. But the clear lesson is that the factions command votes - and cannot be ignored.
E-mail nationally syndicated columnist David Broder at email@example.com.