Gerry Adams has warned the Democratic Unionists it is "decision time" on whether they want to restore powersharing in Northern Ireland.
The Sinn Fein president made it clear that republicans would only strike a deal to form a new administration at Stormont if the DUP gave ground on a series of "rights-based" issues.
Mr Adams claimed the majority of people in the region wanted movement in terms of protection of Irish language speakers and the legalisation of gay marriage, but the DUP was standing in the way.
The Sinn Fein leader also questioned the main unionist party's level of engagement in negotiations to save devolution, claiming they had only met his party for bilateral leadership talks twice in four days.
"The question for the DUP is very, very simple - do they want to be part of the leadership of a rights-based society or not?" he said.
Mr Adams' claims were rejected by DUP negotiator Sir Jeffrey Donaldson.
"I am afraid this is more evidence of Sinn Fein trying to cover their back and trying to prepare the way for yet another walk-out come Friday," said the Lagan Valley MP.
"I predict that Sinn Fein will walk away yet again - just as they did two weeks ago, just as they did in January.
"They are rapidly becoming the party that walks out on the other parties.
"When it comes to commitment, we are there, we are ready to form a government, we are engaging with Sinn Fein and the other parties on all of the issues, we are there every day."
The two parties are involved in set piece talks at Stormont Castle, Belfast, with the three other main parties - the Ulster Unionists, SDLP and Alliance - and the UK and Irish governments.
However, given the DUP and Sinn Fein's position as the two leading parties, devolution can only be restored if they can agree.
Secretary of State James Brokenshire has said he will start formulating legislative steps to either restore devolution or take responsibility for some devolved financial matters over the Easter weekend.
While this has cast Good Friday as a potential deadline for agreement, talks could theoretically reconvene immediately after the Easter break for the period prior to Mr Brokenshire pushing law changes through Westminster.
Mr Adams suggested Good Friday was not make-or-break for his party.
"We are quite relaxed about the British Secretary of State allowing a little bit of extra time for things to be sorted," he said.
"We have to be patient and we have to be resolute and we have to be determined and there is whatever limited time there is left to get this sorted, and that's why we say it's decision making time."
As well as an Irish language act and a commitment from the DUP not to block same-sex marriage, Sinn Fein want to see a Bill of Rights as outlined in the 1998 Good Friday Agreement introduced and the re-establishment of a forum to allow civic society to contribute to the political process.
Sinn Fein is also at odds with the UK Government on how to deal with the legacy of the Troubles.
Mr Adams said his party would reluctantly countenance going back into powersharing without movement on legacy logjams, as they were not a devolved issues, but he said that would not be ideal.
In regard to face-to-face leadership talks with the DUP, Mr Adams said there had been one meeting last Thursday and one on Monday.
"That is not the best use of time," he said.
He added: "We went looking for the DUP yesterday (Monday) evening and they had left."
Devolution crashed in January over a row about a botched green energy scheme.
The subsequent snap election campaign laid bare the other disputes dividing the DUP and Sinn Fein.
Sinn Fein insists the key to progress is implementing outstanding parts of previous agreements.
The DUP, however, claims what Sinn Fein is asking for represents new and unreasonable demands.
Mr Brokenshire instigated the two-week talks process after last month's negotiations to form a new powersharing administration ended in failure.
Parties missed a deadline to get a government up and running within three weeks of March's Assembly election.
Earlier on Tuesday, representatives from business and civic society journeyed to Stormont to deliver an open letter to Parliament Buildings calling on politicians to put aside their differences.
UUP leader Robin Swann said there was a need for a "change in tempo" in the talks.
"The two big parties need to realise there is more to life than what happens in the Stormont bubble," he said.
The Alliance Party has warned that powersharing is being put at risk by vanity-motivated politicians refusing to compromise on minor issues.
Leader Naomi Long said sticking points preventing a deal to save the institutions paled in comparison to the major obstacles overcome during the peace process.
"What we have here is far too precious to simply squander because of vanity projects of individual parties," she said.