Fianna Fail leader Michael Martin accused the Government of being distracted and detached from the job at hand.
He called the speculation surrounding the leadership race an "internal angst" within the party, and said it was detracting focus away from issues such as rent and the health system.
"The health system is in deep trouble", he told Johnathan Healy on Newstalk. "We know that in terms of the crisis in manpower in nursing. Those are the issues Enda Kenny needs to focus on, and everbody else in the Dáil.
"Communication is essential. Engagement with the Dáil is essential."
Speaking about the government's race to pass legislation on rent caps this week, he added that rather than people discussing the rent control issue as a policy, the commentary focused on "Simon v Leo"
"In terms of the manner things were conducted it was not helpful. You can't run something through at the last hour.
"The commentary should be focused on how high rents are going, how can we protect people that are renting, how can we get more people to rent out houses, to be come landlords."
He said not enough council houses are being built, and said Fine Gael's failure to "get a grip" on the housing market was "a damning indictment" of the party.
"I just don't believe in them"
Support for Fianna Fáil has fallen, according to an opinion poll in the Sunday Times published today.
Despite this, the party remains the most popular in the country, with 28% support.
On the results, Mr Martin said: "I have a very healthy skepticism of opinion polls, I just don't believe in them I ignore them, I concentrate on the ground."
Fine Gael are also down 2 at 26%. Sinn Fein are up 2 to 19%. Labour, Triple-A People Before Profit, the Greens, Social Democrats and Renua all make small gains.