The U.S. Census Bureau is counting on a last-minute publicity campaign to boost what the agency's chief calls a disappointing response so far to its first-ever test of counting U.S. citizens abroad.

Only 4,500 forms have been filled out since the test started in February in France, Kuwait and Mexico. There's no exact count of U.S. citizens living overseas so it is impossible to gauge a response rate, though other records show 112,000 Americans in France alone who have registered with the State Department.

The test, as well as another one tentatively planned in 2006, will help determine whether the bureau will officially include citizens abroad as part of the next U.S. head count in 2010.

"It's fair to say that the response has been disappointing," bureau Director C. Louis Kincannon said in an interview last week. "Based on what we've learned so far, it would be a very complicated and expensive job in 2010."

Congress would have to approve such a change to the once-a-decade census. The test costs about $6 million to conduct.

The test ends this month. Kincannon will travel to France this week to attend several events with other U.S. officials there to publicize the count. The bureau says it has expanded its media campaign in France and Mexico, though nothing more is planned in Kuwait.

It is the federal government's first effort to count U.S. nationals living overseas as private citizens. The census already tallies American soldiers and federal workers stationed in other countries.

Census results are used in part to reapportion the 435 House seats among the states each decade according to population shifts. The question of whether and how to count U.S. citizens abroad drew increased scrutiny after the 2000 count, when Utah fell about 80 residents short of being allocated another congressional seat.

The Supreme Court in 2001 rejected Utah's lawsuit contending that about 11,000 Mormon missionaries living overseas should have been included in the state's population.

The overseas forms are available in the three test countries at U.S. embassies, consulates and other locations that Americans may frequent. People can also respond over the Internet.