An analysis obtained by The Canadian Press has found that 32 of 96 tribunal members, including four recent appointees, have either donated to the party, run as Conservative candidates or worked for a Tory candidate.
Testifying before a parliamentary committee late last year, Kenney suggested the 11,000-case backlog, mostly involving those seeking Canada Pension Plan disability benefits, was partly the result of a "rigorous pre-screening process" for tribunal members that required a 12-month vetting period.
"We have taken the patronage dimension of this out of the system," Kenney also told the committee.
"There might be a couple of people on there who have supported my party in the past. I know of only one person personally, who I appointed to the board, with whom I had a pre-existing relationship but who is eminently qualified. These are qualified individuals who are not appointed on the basis of partisanship but on the basis of competence."
In an interview Tuesday, NDP MP Jinny Sims scoffed at Kenney's remarks.
"These appointments have turned out to be patronage, pure and simple, in direct violation of Jason Kenney's commitment to Canadians that he wouldn't turn the tribunal into another trough for partisan appointees," Sims said.
"Do they really reflect the diversity of those seeking benefits or do they reflect the ideology of the party in power? If they only reflect the ideology, then I would say, 'Poor Canadians,' because we have not seen a very kind government towards those who are the most vulnerable."
According to the analysis, there's scant evidence any tribunal member has donated to any other party other than the Conservatives. One member donated to the party just three days before his official appointment in March 2013.
Nonetheless, the tribunal members don't lack qualifications.
One tribunal member in the income-security division, Kelley Joanne Sherwood, is the wife of Kory Teneycke, Prime Minister Stephen Harper's former communications director and now vice-president of Sun News.
She was also an adjudicator on the former Canada Pension Plan review tribunal for several years before her appointment to the tribunal in March 2013. Several other tribunal members were also employed under the old system.
The tribunal, which began operation in April 2013, consists of 74 full-time members and 22 part-timers who hear appeals from Canadians denied employment insurance, old-age security or Canada Pension Plan disability benefits.
It replaced about 1,000 part-time referees on four separate social security panels under the old system.
Thousands of Canadians, some of them seriously ill or injured, are waiting years for appeals due to the growing backlog of cases since the tribunal's inception.
Kenney told the parliamentary committee that the new tribunal inherited an "unexpected" backlog of 7,000 cases from the old system. He also challenged his critics to pore over the CVs of the tribunal members, whom he described as "phenomenal, first-rate people."
Kenney spokeswoman Alexandra Fortier defended the tribunal's hiring record, saying it's a marked improvement over the former system, which had "no comprehensive selection process whatsoever — no examination process and no panel interviews for the vast majority of members."
"We changed that," Fortier said in an email.
"Our government put in place a serious and rigorous selection process based on merit. In fact, the latest selection process saw 739 applicants, of which only 72 applicants passed. The minister appointed from this pool of highly qualified candidates. The majority of the appointees do not have ties to the party.''
Follow Lee-Anne Goodman on Twitter @leeanne25