Mr Donohoe stated his intention to vote for Mr Varadkar in an interview on RTÉ's Morning Ireland.
Minister McHugh said he believed Minister Varadkar would be an outstanding leader of the country who understood issues affecting people right across the State and in particular Donegal. I hold Simon in great esteem, but it's how I have seen Leo respond back to great need is why I'm supporting him.
Labour TD Jan O'Sullivan, has paid tribute to her constituency colleague, saying, "Michael Noonan will be remembered for his contribution to the economic recovery of this country as Minister for Finance, working alongside Brendan Howlin as Minister for Public Expenditure".
"I have many reasons why I will be supporting Leo and I know he would make an excellent leader of the Fine Gael party and an excellent leader of this country".
While Noonan and Kenny have been widely praised for their management of the economy, their Fine Gael party lost a quarter of its seats at elections previous year as voters complained they were not feeling the recovery.
In a statement, Mr Kehoe said Mr Varadkar's "capacity to build a strong support base is testament to his willingness to work with party colleagues".
Under Fine Gael party rules, TDs and senators account for 65% of the votes, while councillors account for 10% and general party members make up 25%.
He also said he will not stand for reelection as a member of parliament. Varadkar himself has been mostly silent, but is due to launch his campaign later today.
One that says to people that if you contribute to the system, the system is there to support you.
"I would like to stress the huge honour and privilege that it has been for me to lead our party for the past 15 years, in opposition and into government on two successive occasions", he said.
However, the next few days will be very telling in terms of the outcome.
Meanwhile, in Dublin, Leo Varadkar has made his first public appearance of the leadership campaign.
He advised people not to confuse someone who is good at putting deals together with someone who is weak.
The address will take place at lunchtime in the city centre where the Taoiseach will also meet members of the Global Irish Network and clients of Enterprise Ireland.