The crucial vote is expected in the House of Commons some time around 9 pm.
Mr Eastwood said any move by the British Prime Minister to ditch the backstop would be “catastrophic” and would send the economy in Northern Ireland into an “unmitigated disaster”.
Speaking from London, the Foyle MLA said: “This is not a game. Those in the Tory Party and the DUP who think they can play with fire when it comes to Northern Ireland need to think again.
“Just last week we saw hijackings and bombings back on our streets in the North. Our peace is very fragile, our communities are frustrated and our economy is dwindling.
“The stability we have in Northern Ireland should not be threatened – not by the DUP, not by the British State – and certainly not by a group of extreme right wing Brexiteers who don’t care about our people.
“Ditching the backstop would be catastrophic. It will send our economy into an unmitigated disaster and our communities into a socio-political crisis.
“I’ll be telling MPs today, that the stakes are too high. The backstop must be banked. Failure to do so will result in chaos right across these islands – that I believe no one wants.
“While the DUP may feel emboldened – they are ignoring the wishes of the people of Northern Ireland – and people are noticing.
“Meanwhile, Sinn Féin sit on their hands – abstaining not just from Westminster but from power, robbing our communities of a voice.
“Today the SDLP once again is leading the fight against the hard right and against the Tory Party.
“Others need to get real and join us – before it’s simply too late,” added the SDLP leader.