The Clinical Medical Director at Cork University Hospital has said it is inconceivable to think that healthcare staff would be granted extended leave over the Christmas period.
Speaking on RTÉ’s Morning Ireland, Dr Mike O'Connor said this may have happened 20 years ago but was not the case anymore.
Dr O'Connor said it was "bordering on disingenuous and insulting" to HSE staff to suggest that significant numbers take extended leave over this period.
He estimated that less than 10% of hospital consultants will be on leave in January.
Mr Varadkar came under criticism on Tuesday after he said that hospital consultants, nurses and other medical professionals should not be on extended leave over Christmas and the first two weeks of January to ensure that every hospital bed is open.
Dr O'Connor agreed with the Taoiseach that things could be "a little more intense" over the Christmas period but said it was "not much different from the [rest of the] year".
He added that staff knew what to expect from this period and that they were primed for it.
He said the winter plan had a number of key issues, such as maximising the number of key decision-makers available on-call and on-site at all times, as well as maximising discharges.
Dr O'Connor said many patients would leave hospital over this period because they wanted to be at home.
He said it was "bogus" to talk about winter pressures because hospitals were under pressure all year round and there was no collective, collaborative plan to resolve the trolley issue.
Dr O'Connor said 40,000 people would spend more than 24 hours on a trolley this year and 12,000 of these patients would be over 75.
In the Dáil, opposition parties criticised the Taoiseach and the Minister for Health over their comments in relation to hospital staff and Christmas holidays.
During Leaders' Questions, Fianna Fáil Deputy Dara Calleary said it was unacceptable that Mr Varadkar and Simon Harris would blame frontline staff who are working in challenging conditions.
Tánaiste Simon Coveney said the Taoiseach was not blaming anyone.
He said Mr Varadkar was pointing out that those with responsibility for leadership in hospitals needed to ensure there would not be a skeleton staff at times of the year when patient care needs to be prioritised.
Mr Coveney said Minister for Health Simon Harris reinforced that, to ensure that rosters and key team leaders and sufficient staff are in hospitals during the winter period and the first two weeks in January, when hospitals are under pressure.
He said the Taoiseach addressed the issue "head on and directly" when he was questioned on the matter.
Mr Coveney said team leaders needed to be in hospitals, in person, regardless of whether it is Christmas time or not.
"The idea that we can pretend that rostering is not an issue and that in the next few weeks and months that we shouldn't be preparing for that and having an honest conversation about it with people who are well able to engage in that honest conversation, in my view is political correctness gone mad," Mr Coveney said.
Sinn Féin TD Pearse Doherty accused the Taoiseach of resorting to "gutter politics" and called on the Tanáiste to apologise for Mr Varadkar's remarks.
He said Mr Varadkar was trying to shift the blame for the crisis, and he had "some cheek" criticising them when he himself was on holidays in Miami during the last overcrowding crisis.
Independent TD and GP Dr Michael Harty said the Taoiseach should have targetted the Department of Health and the HSE because he said emergency department overcrowding is an all year around issue.
He asked Mr Coveney when "real transformation funding" would be provided to transform the health service, because he said it needed to be over and above the normal health vote.
Mr Coveney accepted that it was a 12-months-of-the-year challenge and problem, adding that capacity was "a huge issue" across so many hospitals.