Barton, 28, has been offered a lucrative deal to join Neil Warnock's team after being told he can leave Newcastle on a free transfer and he has travelled to London to discuss a deal.
The former Manchester City star had indicated he would prefer to stay with Newcastle, but the Magpies have made no attempt to offer him a new contract following Barton's recent war of words with Newcastle owner Mike Ashley and his directors.
Barton took to micro-blogging website Twitter to criticise the club's transfer policy and a perceived lack of ambition following the sales of Andy Carroll and Jose Enrique to Liverpool.
QPR boss Warnock hopes to take advantage of the situation and his newly-promoted club, bolstered by the financial clout of new Malaysian owner Tony Fernandes, are reported to have offered Barton wages of £80,000 a week to move to Loftus Road.
However, Barton claimed he was still considering his options when asked about the transfer as he left QPR's training ground on Thursday.
"The latest is that we are just completing the final stages of the medical, so we will just get that over and done with and then see where we are at," he told Sky Sports News.
"I have not made a final decision just yet, but speaking to the club, they have got big ambitions and I had to come down and hear what they have got to say and go through the formalities of the medical side of it just in case any deal does happen."
Asked if he was optimistic of joining QPR, Barton added: "I am not sure. There are still a number of things to be sorted out, but it's a process you have to take step by step, and that's the stage we are at at the minute."
Joey Barton has medical with QPR
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