Taoiseach Leo Varadkar has said Fianna Fáil shouldn't be "precious" about his claims that some of its TDs are "backwoodsmen" that oppose social progress.
It comes as the divisive issue of abortion has been brought into the election debate.
Micheál Martin criticised Mr Varadkar's remarks as "beneath the office of An Taoiseach" and Michael McGrath accused him of a "personalised, nasty" approach to politics.
But Mr Varadkar hit back last night saying: "I don't think Fianna Fáil should be getting too precious."
He branded remarks made by Mr Martin at the weekend - when he argued Fianna Fáil represents working class people and Fine Gael members "come from a more privileged background" - as "very disrespectful".
Mr Varadkar argued it was not in line with Fianna Fáil's slogan of 'An Ireland for all'.
He said: "We should represent people regardless of what background they come from."
Separately, Mr Varadkar expanded on his "backwoodsmen" comments, saying he was referring to 21 Fianna Fáil TDs that opposed the holding of a referendum to repeal the Eighth Amendment on abortion.
He also claimed on RTÉ Radio that Fianna Fáil will be less enthusiastic about progressing gender equality.
One of the Fianna Fáil TDs who voted against holding the referendum, Shane Cassells, last night claimed Mr Varadkar had "gone into the gutter" with the remarks about Fianna Fáil TDs. Mr Cassells argued the comments "belittle people who stood up for the rights of the unborn".
Mr Varadkar responded saying: "I have the highest respect for people, no matter how they voted in the referendum.
"What those 21 TDs did was something different. They tried to prevent a referendum from happening at all.
"They didn't want the Irish people to have their say."
Mr McGrath said of Mr Varadkar's attack: "They go low, we go high. We're focused on the issues that really matter to people."
He brushed aside a question about Fianna Fáil colleagues who sought to block the referendum taking place saying: "We have had the referendum. The Irish people have had their say... There was a decisive result. The result has now been implemented through legislation and that is the way that it should be."
His party colleague Stephen Donnelly insisted Mr Varadkar's comments on his party's enthusiasm about gender equality are "nonsense" and the attacks a sign of "panic" in Fine Gael.
Last night Fine Gael candidate Deirdre Duffy waded into the debate. She said her party will prioritise legislating for 'safe access zones' so women can access healthcare and abortion services without impediment.
Ms Duffy expressed extreme concern at the prospect of a Fianna Fáil government as its manifesto doesn't mention 'safe access zones'. The Dublin Central candidate said: "When it comes to women's healthcare and access to abortion services, Fianna Fáil is the party of no."