Wednesday interested in O’Dea
Bolton Wanderers and Burnley are also keen on the 25-year-old who is now with the Ireland squad preparing for Euro 2012.
The Owls have also been in talks with Crystal Palace defender Anthony Gardner over the last few days but have yet to finalise a deal.
Now 31, Gardner struggled with injuries at former club Hull City but started 25 games for Palace last season in the Championship.
Rotherham United manager Steve Evans says the coming days are likely to be ‘crucial’ in terms of team strengthening.
The Millers have already signed six players and sold striker Lewis Grabban to Bournemouth but Evans said: “It is essential we get this right if we are to enjoy the season ahead.”
Grabban’s departure for an undisclosed fee followed the capture of strikers Daniel Nardiello and Kayode Odejayi, midfielder Michael O’Connor, defenders Ian Sharp and Nicky Hunt, and goalkeeper Scott Shearer.
Evans still wants other players to leave the Millers as part of his summer shake-up.