By Christopher S. RugaberWASHINGTON -- When conspiracists suggested Friday that the Obama administration had engineered a sharp drop in unemployment to aid President Barack Obama's re-election, the response was swift. Career government officials, economists and even some Mitt Romney supporters issued a collective sigh. The staffers who compute the U.S. unemployment rate work in an agency of the Labor Department. Officials who have overseen the work say it's prepared under tight security with no White House input or supervision. "To think that these numbers could be manipulated. ... It's impossible to do it and get away with it," said Keith Hall, a former commissioner of the Bureau of Labor Statistics, the agency that calculates the unemployment rate. "These numbers are very trustworthy," said Hall, who was appointed by President George W. Bush and whose four-year term ended in January. > > Bull or Bear? Vote in Our Poll The figures that produce the unemployment rate are crunched by several dozen people at the bureau. The only BLS employee appointed by the White House is the commissioner, who operates independently of the White House. The job is now vacant but is being handled by Acting Commissioner John Galvin, who has worked at the BLS for 34 years. Yet conspiracy theorists came out in force Friday after the government reported a sudden drop in unemployment a month before Election Day -- to 7.8% for September from 8.1% in August. Their message: The Obama administration would do anything to ensure a November victory, including manipulating unemployment data. Labor Department officials, joined by Democrats and some Republicans, called the charges implausible. That didn't stop the chatter. The allegations were a measure of how politicized the monthly unemployment report has become near the end of a campaign that's focused on the economy and jobs. The conspiracy erupted after former General Electric ( GE) CEO Jack Welch, a Republican, tweeted his skepticism five minutes after the BLS announced the unemployment rate at 8:30 a.m. Eastern time.