Ben Fletcher, who worked for Ms Jenkyns’ team in the 2015 election, posted the five-page letter on Twitter attacking the Morley and Outwood candidate who provided one of the big shocks of the 2015 election by unseating Labour’s Ed Balls.
But Ms Jenkyns said she had “given her all” to being Morley and Outwood’s MP.
Mr Fletcher’s letter said: “I thought Andrea to be a candidate who truly cared about putting the people of Morley and Outwood ahead of her own personal ambitions. I thought Andrea to be a candidate who truly cared about facts and decency.”
But he added: “What has become clear since 2015 though, is that the Andrea Jenkyns who stood to represent you all then, is not the same Andrea Jenkyns who took up the job. Since 2015, Andrea has continued to pursue an increasing far-right ideological agenda while ignoring the basic principles of decency and humanity that she once led me and others to believe she truly cared about.”
Mr Fletcher took issue with Ms Jenkyns’ voting record, and accused her of being more interested in keeping her party happy than fighting for equality.
But Ms Jenkyns said: "Ben was involved in my campaign more than four years ago.
“Since then, I've given my all to serving the people of Morley & Outwood as an MP in the best ways I possibly can.
“On Thursday, I hope people across the constituency will vote for me again so we can deliver a majority Conservative Government and get Brexit done, which I know many, many people in Morley and Outwood want to see.
“Then we can focus on the priorities here including the NHS, policing, schools and tackling the cost of living."
Mr Fletcher also highlighted Ms Jenkyn’s role with the not yet in existence thinktank the National Centre for Higher Education Policy, for which she gets paid £25,000 a year and slammed her expenses claims.
Ms Jenkyns told The Guardian the new thinktank would be called Rise – the Research Institute for Social Mobility and Education and said: “Social mobility is a big passion of mine, having been the first in my family to go to university, and having started at Greggs bakery at 16 and working my way up into management in the retail sector.”
The other candidates standing in Morley and Outwood are Chris Bell (Green Party), Craig Dobson (Liberal Democrats), Deanne Ferguson (Labour), and Dan Woodcock (Yorkshire Party).