Labor won't nominate a renewable target

Federal Labor insists it will not nominate a specific figure for a pared-back renewable energy target.

The government has turned to the Senate crossbench after talks with the opposition hit a wall.

Opposition environment spokesman Mark Butler says Labor is prepared to accept a 2020 target around the mid to high 30,000 gigawatts, but not the government's 32,000 offer.

"They've got to make a move and put a more reasonable offer on the table," he told ABC radio on Wednesday.