A new Gallup poll shows President Barack Obama leading significantly over Presidential nominee Mitt Romney among the 24% of American working voters who are classified as professional, and among the 13% who are service workers.

However, the two are tied among clerical and office workers. Romney leads among all other job categories, including voters in the farming, fishing and construction sectors. According to the poll, Romney also has an edge among executives and managers.

The Gallup findings are based on an aggregate of Gallup Daily tracking interviews conducted April 11 – May 21. Workers were categorized based on their responses to a question asking them to state the general type of work they do, and coded into one of the 11 categories that the U.S. federal government uses to classify workers.

Overall, the sample of working voters show Romney and Obama statistically tied, with Romney at 47% of the vote and Obama at 45%.

The results of the poll show that workers’ vote choices are significantly related to the type of work they do.

The first group of voters with postgraduate education show strong Obama support. However, the second category of workers — service workers constituting 13% of working voters, favor Obama over Romney by 13 percentage points.

The third-largest category of workers that include managers and executives – 10% of working voters – favors Romney by seven points over Obama.

Clerical and office workers – 7% of working voters – are evenly split in their vote preferences.

Romney’s biggest lead is among the 2% of working voters who are classified as farming, fishing or forestry workers. Their vote choice is 66% Romney, 29% Obama.