Nothing at all to do with the trade embargo imposed by the United States.
Trump wants to hurt Maduro, but in reality he is making all Venezuelans suffer.
The US used to import a large amounts of oil from Venezuela. In recent years the US has invested heavily in fracking to the extent that it is self sufficient in oil, and no longer needs Venezuelan crude.
That, together with the embargo has done for Venezuela.
Also, if you really think that a Labour win would've resulted in the kind of thing the people of Venezuela are currently suffering from, you really are living in cloudcuckooland.