WASHINGTON - Immigration-related felony cases are swamping federal courts along the Southwest border, forcing judges to handle hundreds more cases than their peers elsewhere.

Judges in the five, mostly rural judicial districts on the border carry the heaviest felony caseloads in the nation. Each judge in New Mexico, which ranked first, handled an average of 397 felony cases last year, compared with the national average of 84.

Federal judges in those five districts - Southern and Western Texas, New Mexico, Arizona and Southern California - handled one-third of all the felonies prosecuted in the nation's 94 federal judicial districts in 2005, according to federal court statistics.

While Congress has increased the number of Border Patrol officers, the pace of the law enforcement has eclipsed the resources for the court system.

Judges say they are stretched to the limit with cases involving drug trafficking or illegal immigrants who have also committed serious crimes. Judges say they need help.

"The need is really dire," said Chief Judge John M. Roll of the District of Arizona. "You cannot keep increasing the number of Border Patrol agents but not increasing the number of judges."

A bill by Sen. Pete V. Domenici (R., N.M.), and cosponsored by Sen. Jon Kyl (R., Ariz.) and Texas Republican Sens. John Cornyn and Kay Bailey Hutchison, would add 10 permanent and temporary judges in Arizona, New Mexico, and Southern and Western Texas. That proposal and others like it have gone nowhere in the last two years.

The entire federal court system is affected, from U.S. marshals to magistrate judges. The bottleneck has even derailed enforcement efforts.

During a push to crack down on illegal immigration last fall, Customs and Border Protection floated a plan for New Mexico that would have suspended the practice of sending home hundreds of illegal immigrants caught near the border with Mexico. Instead, those people would be sent to court.

Then New Mexico's federal judges reminded the Border Patrol that they lacked the resources to handle the hundreds of new defendants who would stream into the court system every day.

Border Patrol eventually dropped the idea. Officials said they could not get all the necessary agencies to agree to it.

It is estimated that more than one million people sneak across the southwestern U.S. border and enter the country illegally every year. In Arizona, the busiest entry point for illegal immigration, state officials believe almost 4,000 people tried to enter every day in 2006.

In recent years, Congress has focused on increased enforcement.

The Border Patrol has almost 2,800 more agents than the 9,821 it had in September 2001. An additional 6,000 National Guard troops have provided logistical support to the Border Patrol since last May.

Congress has made available more than $1.2 billion for reinforcements, including fences, vehicle barriers, cameras and other security equipment.

Homeland Security officials say the increased security is working. In Yuma, President Bush said that the number of people apprehended for illegally crossing the southern border into the United States has declined by nearly 30 percent this year.

Court officials, however, say they are in crisis mode trying to deal with all the defendants.

Rep. Darrell Issa (R., Calif.), a staunch opponent of illegal immigration, has urged U.S. attorneys and courts to prosecute more illegal immigrants and pushed for more resources for both. But he has discovered that while his colleagues who do not represent a border district are eager to add Border Patrol officers, many do not realize the effect that will have on the court system, his spokesman said.

Even lawmakers from border states say they cannot justify adding judges in one district when other districts also need them.

Court officials say they have had to be creative. Visiting judges help in some districts. In Arizona, magistrates hold sessions on the weekends and have seen as many as 150 defendants in a day.