Venezuelan soldiers instrumental in keeping Maduro in power are backing rival Guaido and abandoning their posts
Video report by ITV News Correspondent John Ray
He still wears the uniform so feared back home.
The top-to-toe black of the FAES, Venuzuela’s special police, blamed for the deaths of many opposition supporters.
But Williams Cancino tells me he is no longer prepared to follow orders; and can no longer be loyal to the regime he served for so many years - not when his own salary isn’t enough to feed him or his family.
"We all feel it in our flesh," he tells me.
"The army, the police. Every person who lives in Venezuela feels the suffering that is created by Nicolas Maduro, the usurper," he adds.
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Last Saturday he travelled from the capital, Caracas, to the border and calmly walked across.
"I've been planning it for some time," he says, explaining how he first made sure his girlfriend and his mother had escaped the country.
"Ninety per cent of the army and the police would defect if they could," he claims.
I ask that if morale is so bad, why more don’t follow.
"My comrades aren’t doing so because they are afraid of being jailed, or being killed, or someone will go after their family."
Colombian authorities say more than 400 soldiers and police officers have defected.
We watch as a young army private surrenders to Colombian troops.
"I would rather die or live on the streets than kneel before that dictatorship for another 20 years," Andry Rosales said, reduced to tears as he speaks.
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Each defector is a crack in the regime - but nothing like enough to signal its collapse.
And that caps a week of set backs for the opposition.
Last Saturday they tried to drive a convoy of aid over the border here; in the hope that would undermine the authority of the Maduro government - and encourage the military en mass to swap sides.
Instead, there's been a steady flow of junior ranks, and not the flood they need.
Meanwhile, the coalition of countries who recognise opposition leader Juan Guaido as the rightful president is split over the threat of force – taking that option off the table, for now at least.
Despite the closure of official crossing, Venezuelans are still fleeing the crippling poverty and economic meltdown back home.
But now have to take illegal routes out the country.
One family we met stumbling over rocks and a river into Colombia had sold their house and car and every possession they couldn’t carry for the chance of a fresh start.
"Maduro must go soon,'' said Samuel Tineo. ''We have given up everything to leave and we do not know what our destiny will be."
For the moment, it’s the people who are moving, and Maduro who is staying put.