Leeds is on track to return to the Premier League and is looking for a goalkeeper with extensive experience in the Premier League. Johnstone meets these criteria, having played in the league before.
Johnstone, who is an England international, is not currently playing regularly for Wolves due to the presence of Jose Sa. He may be open to joining Leeds if he receives regular playing time.
Johnstone's last match was in December, when Wolves lost to Ipswich Town.