Why did Voldemort use Triwizard Tournament to get Harry to the Graveyard? [duplicate]

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• Why was the Triwizard Cup used as the portkey? 11 answers

Why not just arrange moving Harry to the graveyard when it was convinient to Voldemort and proceed with the spell?

Barty was already installed at Hogwarts, Dumbledore and others fell for it, Barty was perfectly capable of arranging the transport at any moment. Or someone else could have done it in Hogsmeade. Or they could wait till when Harry is back in Privet Drive.