Brazilian negotiators have been accused of using strong-arm tactics at Rio+20 to secure a deal before heads of state start arriving for the Earth Summit later this week.

The ghost of the Copenhagen talks — which ended with disappointment and recriminations — is driving the attempt to force through an agreement, despite risks it could backfire spectacularly, said a senior source at the negotiations.

Brazil‘s spokesman said on Monday he was optimistic a compromise text could be approved by Tuesday evening.

But frustrated delegates are now considering blocking the proposed text because of its lack of ambition and the “aggressive” tactics employed by the host nation.

“They are doing this more because of how they will look in the eyes of the heads of state and their desire to show a successful conference in the sense that it did not break down or that there was no outcome,” said the source. “If they carry on with these tactics the risk is that some delegations will feel they may need to block this because it is not ambitious enough.”

Luiz Alberto Figueiredo, the Brazilian foreign ministry spokesman said on Tuesday that consensus was close on proposals to strengthen Unep, manage the world’s oceans and establish sustainable development goals.

This appeared to mark progress after weeks of procedural wrangling and divisions between rich and developing nations, but the host’s tactics are now being questioned.

“They are speaking with two tongues; on the political level they say they want ambition and on the civil servants level they are being extremely aggressive in closing down the conversation,” said the source. “For the Brazilians, it is more important that the process is seen to be efficient rather than effective. The reality is that the Brazilians are around during the negotiations, then they go back to their room and they say they have taken all the comments and thoughts into account and then just produce their own text.”

The hosts denied bullying tactics. “The Brazilian role in the consultations has been praised by the UN and by virtually all countries. The developed countries also seem to be satisfied,” said a senior official.

Other delegates were more sympathetic to Brazil’s efforts to reach a compromise, saying the host had done its best to incorporate a wide range of views. But there was widespread frustration at the weakness of the compromise document and its lopsided emphasis on the economy above than the environment.

“We want there to be more ambition so that it actually leads to sustainable development. At the moment, there is a risk that instead of the future we want, we will go back to the past we had,” said an EU official.

Several member states are concerned that a weak outcome is becoming inevitable. Little is expected from the US, which is preoccupied with a presidential election and strong domestic hostility to action on climate and other environmental issue. The G77 is divided on several major issues.

Europe, South Korea and Japan have told the Brazilian government they would like to see more concrete goals, timelines and measures to achieve a “green economy”, and argued that the current draft is inadequate to counter the risks posed by degrading ecosystems and diminishing resources that could be approaching a tipping point. Other nations, including New Zealand, are also pushing for more ambition on issue like the removal of fossil fuel subsidies.

Civil society has criticised the watered-down document.

“What we are seeing in Rio are incredibly weak negotiations which do not produce the results required to lift people out of poverty and stop environmental degradation. Rio+20 is creating a black hole of low ambition and little substance,” says Kit Vaughan, CARE’s Climate Change Advocacy Coordinator.

Lasse Gustavson, head of WWF’s delegation, said: “While we think some of the new text is a good base for the future, such as the language on oceans, we see a lopsided victory of weak words over action words ,with the weak words winning out at 514 to 10.”