FEDERAL politicians are locked in a stand-off over water, with the planned takeover of the ailing Murray-Darling Basin hanging in the balance.
But the plan has hit a brick wall in the Senate.
The coalition, the Greens and independent senator Nick Xenophon have forged an alliance, saying the takeover does not go far enough and that the laws should be toughened up.
Without their support, the water takeover cannot go ahead because Labor does not hold a Senate majority.
Opposition senators have demanded that Victoria's controversial Sugarloaf pipeline, which will take up to 75 billion litres of water out of the basin each year, be scrapped.
They want an overall basin plan written well before the government's 2019 deadline and much more money spent on waterproofing irrigation infrastructure.
And they want all new mining projects to have to prove they will have no impact on water flows before being given the green light.
Opposition water spokesman Greg Hunt said the government's water plan was not good enough.
"We have put together a historic coalition to save the Murray," he told reporters in Canberra.
Mr Hunt told the government to "come and talk" about a way forward.
Greens water spokeswoman Rachel Siewert said there was no point passing the government's soft water plan.
"It's not time to sit around and make small, incremental changes to the Murray," Senator Siewert said.
"We need a much more aggressive approach."
She said the Senate was "fair dinkum" about its changes, and it was up to the government to consider them.
Lobby group GetUp! joined the Senators to present a petition of 47,000 signatures from people concerned about the Murray's future.
The government is trying to pass changes to the existing Water Act. The Senate has heavily amended those changes, and is still debating the act.
When passed, it will go back to the lower house.
AAP