Harrington has appeared in six editions of the biennial contest against the United States, whereas Colsaerts will become the first Belgian to feature in it in Illinois.
A survey by HowDidiDo, Europe's largest golfing community, showed that only a quarter of golfers disagreed that the in-form Colsaerts was more deserving of a spot than three-times Major winner Harrington.
More than 2,300 contributed to the vote
HowDidiDo managing director Barry Dyett said: "There has been some criticism in certain quarters over the captain's pick but it seems our members — who are all active club golfers — have faith in José María Olazábal.
"The high response rate shows it is not just an emotive subject among golfers, but also that the decision is a sound one.
"Whether you're a Ryder Cup captain or just an enthusiastic observer, however, such selections are, of course, subjective and the only thing that will ultimately matter is the performance over the three days later this month."
Irishman Harrington helped Europe to win the Ryder Cup in 2002, 2004, 2006 and 2010, and was on the losing side in 1999 and 2008.
Colsaerts is the longest hitter on the European Tour, and with US captain Davis Love III having set up a particularly long course at Medinah, his selection seems to have gone down well with active golfers in the UK.
- Sports & Recreation
- Padraig Harrington