Mary Lou McDonald says she would call for an election if it were not for the ongoing coronavirus pandemic.
Sinn Féin has polled as the most popular party in the country a number of times in the months since February's elections, and many have speculated that members of the party were pleased to head into Opposition, leaving them free to criticise the Government in difficult times.
However, Ms McDonald insists she is far from happy to be in Opposition.
"I'm not delighted at all," said Ms McDonald. "I'm actually really anxious.
"I think it's ironic really that the argument was saying that they had to go in together to provide stability and certainty, and that above all else Sinn Féin had to be kept out at all costs.
"Now what we've had, arguably the most chaotic and dysfunctional administration that we've ever seen.
"They all, Green Party included, carry a level of responsibility for the kind of chaos of Government that we've seen and I think it's to such an extent that it's actually unnerving to people in times that are very difficult and very challenging.
"I do not delight in failure. I'm as frustrated as anybody else watching just how poorly this Government is performing. I'm anxious now for people."
Since its most successful election in February, the party has taken on a number of staff and has undergone a significant frontbench reshuffle.
Shock was expressed when Fingal TD Louise O'Reilly was moved from the health portfolio and into business and enterprise, and replaced by David Cullinane.
"Louise is the type of TD that I could put to use in any brief and she would perform," said Ms McDonald.
"I am very conscious that the whole issue of work and unemployment is going to loom very large, very, very quickly and not least youth unemployment.
"It also came to my attention that Leo Varadkar has workers' rights on his watch, a fact that sent a shiver down my back, so that was a factor as well, but she is hugely talented, it's actually a reflection of her strengths and her very considerable talents rather than anything else."
More than 100 days since the formation of the Government, the problems raised in the election have got considerably worse, said Ms McDonald.
"I think it's astonishing after 100 days and we still don't have proper rent controls or proper protections for people in rented accommodation," she said.
The party underwent sustained criticism during the election over the treatment of Paul Quinn's family after MLA Conor Murphy accused the murder victim of being involved in criminality.
Since, the party has continued to undergo criticism about social media trolls claiming to be associated with or supporters of Sinn Féin.
One member resigned this year after it was found he used an anonymous account to abuse people online.
"You can have a political debate without being abusive, and I get my own fair share of abuse," said Ms McDonald.
"This notion that somehow this is a Sinn Féin thing, it's just not.
"There are people across the board who will misuse social media platforms and they should simply stop, and anybody who is behaving in that way and think that they're acting on behalf of the Sinn Féin party, let me make it clear, they are not.
"I don't think anybody could reasonably expect any political leader to be accountable for the hundreds of thousands of people who voted for you, that's not a reasonable ask.
"And, certainly, if it gets to the point where people feel threatened or harassed or then they need to go to the authorities, I've done that myself in the past because it's not acceptable."