The U.S. Census Bureau expects to add up to 750,000 workers to its payroll by May, a hiring binge that could knock the unemployment rate down by as much as a half-point.

The once-a-decade census is coming at the best possible time for President Barack Obama and congressional Democrats, who have taken political lumps for more than a year over a jobless rate that stands at 9.7 percent. 

{mosads}Some think the administration will get good news as soon as the next monthly labor report, which will be released the first Friday in April. 

“This is the best-timed census you could ever dream of,” said Heidi Shierholz, who tracks the labor market at the left-leaning Economic Policy Institute. She believes the March unemployment report will show the economy added jobs instead of subtracting them. 

If it happens, it will be only the second positive-numbers jobs report in more than a year. But in this case, it could lead to further positive job numbers in the months ahead.

Census officials warn that politicians shouldn’t get too excited. 

Hires for the 2010 census are temporary and part-time; the average employee works 19 hours a week for six weeks, according to Wendy Button, chief of the decennial recruiting branch of the Census Bureau. 

Almost all of those hired will be doing “non-response follow-up work” that involves going door to door to collect information from people who did not return their census forms. 

How long employees are on the payroll depends on how long it takes to collect the information, but the bureau expects its payroll to peak in May and to begin winding down in June. 

That means hundreds of thousands of people who find work through the census will need to find new jobs later this summer. 

Button also wants to dispel the notion that 1.2 million people are being hired by the Census Bureau, something she said has popped up in published reports. The Census Bureau is filling 1.2 million positions in the fiscal year, but some workers will fill multiple positions. 

“This is in no way going to solve our unemployment situation,” said Button. “It’s going to be a blip. A big blip, but it’s going to be a blip.”

Still, it’s a blip that could help Obama and Democrats. 

A February report by the Department of Commerce estimated that the hiring could reduce the unemployment rate by .5 percent in April, when hiring is at its peak. 

That has Democrats hoping the economic tide is turning in their favor as attention moves to the midterm elections in November. 

The Census has already begun its hiring. It had added 41,000 employees as of February. 

Unemployment is calculated by dividing the share of people who are unemployed and actively looking for work by the number of people in the labor force. 

If those hired by the Census Bureau are jobless and have been actively looking for work, they will cause the unemployment rate to fall. 

But if those hired are people who had previously given up looking for jobs, they won’t be counted as reducing the unemployment rate. 

Unemployment actually rose in 2000 when Census hiring was at its peak, but that census took place during a period of low unemployment. 

Because this year’s census is taking place during a time of high unemployment, the Commerce report said it’s possible a greater number of hires will be people who are now counted as unemployed. 

Either way, Shierholz said, unemployment is likely to stay high. 

She expects the economy will add jobs, but estimates it will need to add more than 100,000 jobs per month to get the unemployment rate to fall, something that will require significant, sustained economic growth. 

Still, the census could provide a spark of positive jobs numbers that might offer a bridge to later this year, when economists have more optimism that the economy will be strengthening.

In other words, while it is a blip, it’s a blip that could boost the political fortunes of the party in power.