A former Scottish Greens leader and MSP has joined the Scottish Labour Party.
Robin Harper, who was the UK's first Green parliamentarian, criticised the SNP and his former party for failing on the environment.
In a letter to voters in Edinburgh, he said voting for Labour in this election was the "only way to get rid of the Tories".
Last year, Mr Harper resigned his life membership of the Scottish Greens. saying he believed the party had "lost the plot".
In his resignation letter he told co-leader Patrick Harvie he was concerned by the the party's pro-independence stance and its position on transgender rights.
Mr Harper served as a Lothians MSP between 1999 and 2011 and was co-convener of the party from 2004 to 2008.
Writing to voters in Scotland's capital city, Mr Harper said: "I desperately want to see the back of this Conservative government, who have crashed our economy, degraded our political life and failed to tackle climate change.
“The SNP, and until recently their Green coalition partners, have also failed to take action on the environment."
He added: “Labour is the only party with a plan for combatting climate change and harnessing the potential of the green industrial revolution.
“This election provides us with a now-or-never opportunity to remove the Tories from power and end the chaos, failure and inaction that has marked their fourteen years in government."
Ian Murray, Labour candidate for Edinburgh South, said he was delighted Mr Harper was helping his campaign.
“Robin is one of the most respected parliamentarians of the devolution era," he said.
“His decision to join the Scottish Labour Party demonstrates that we are the only party with a clear plan to deliver on Scotland’s green potential – creating thousands of clean energy jobs and cutting energy bills for good, with GB Energy paid for by a windfall tax on oil and gas giants."