Chris Summers, the Labour candidate who will be challenging the London Mayor for the seat, says he has been reliably told that Mr Johnson will not attend three planned hustings in the run-up to the national polls.
The hustings referred to by Mr Summers are at Brunel University on March 19, Yiewsley Baptist Church on April 26, and a third is being organised by Hillingdon Inter Faith Network.
Mr Summers said: “Apparently Mr Johnson has said he will only take part in one hustings in ‘early April’.
“But I have no idea what hustings he is referring to as I am not aware of any planned hustings in early April. So it’s quite possible he won’t turn up for any hustings.”
The Uxbridge and South Ruislip Tory seat is up for grabs after current incumbent John Randall announced his retirement.
It is regarded as a Conservative safe-seat but Mr Summers warned Mr Johnson could be in for a shock on Election Day. He said: “By refusing to attend three separate hustings Mr Johnson is showing his contempt for voters.
“I believe a lot of people will find his cavalier attitude quite disgusting and it gives an insight into the sort of MP he would be if was elected - absent and uninterested in the people of Uxbridge and South Ruislip.
“This election is not a foregone conclusion and Mr Johnson might be in for a rude shock on May 8.”
The Conservative group would not confirm or deny Mr Johnson's appearance at hustings, but Tory council leader Ray Puddifoot had this advice to Mr Summers. He said: “Chris must run his own campaign to the best of his ability – Boris will be doing the same.”
Mr Summers will be ramping up his efforts to win the seat next month when Tottenham’s Labour MP and Mayoral front-runner David Lammy visits Uxbridge on March 20. His visit will be shortly followed by former Olympics minister Tessa Jowell to Brunel University Sports Club on March 27.