The young midfielder is currently out on loan with Scottish Championship side Partick Thistle.
The ‘outstanding’ McKinnon signed a new three-year contract in June, but this might not put off Newcastle.

McKinnon played his first match for Rangers at the end of last season, and scored an emotional debut goal against Hearts.
He’s started this season brilliantly too, starting every game for Partick and already netting twice for The Jags.
He scored a brilliant wonder goal on Saturday against Arbroath, dribbling past two defenders before calmly finishing.
McKinnon typically plays as a traditional central midfielder or in a slightly more advanced role.
Cole has also impressed Rangers manager Giovanni van Bronckhorst, and probably isn’t far away from the first team at Ibrox.
Newcastle considering McKinnon bid
Eddie Howe has just completed his first summer transfer window in charge at Newcastle.
The Magpies broke their transfer record to bring in forward Alexander Isak.
However, the majority of Newcastle’s business was very sensible.
Howe appears to want to improve his squad gradually, despite the vast riches he now has available.
Although Isak and Sven Botman are under 23, McKinnon would be signal Newcastle are looking more long-term in the transfer market.

Newcastle brought in Dan Ashworth from Brighton to lead their recruitment policy.
The Seagulls’ priority under Ashworth was to find young hidden gems from around the world.
Newcastle considering a bid for McKinnon suggests he’s already got to work implementing that policy at St. James’ Park.
McKinnon’s long-term future at Ibrox is safe after signing a new deal, but the lure of the Premier League might be hard to turn down.
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