The Sunderland boss is ready to offer £6million for Onuoha, who has been on loan at the Stadium of Light this season and has proved a hit at right back and as an emergency centre half.
If he can secure a permanent deal in January for the 24-year-old defender, who has relished playing weekly first-team football on Wearside, Bruce has prepared an offer to take Sunderland-born England winger Johnson on loan for the rest of the season.
Double deal: Sunderland boss Steve Bruce wants to sign both Adam Johnson (left) and Nedum Onuoha (right)
A year ago Bruce and his chairman Niall Quinn were certain they had secured Johnson from North East rivals Middlesbrough in a £6m deal, only for City to blow them out of the water with a last-minute bid.
Cash-strapped Boro accepted City's lucrative offer, which topped £8m with its add-ons and Johnson was attracted by City's £60,000-a-week wages.
The 23-year-old made a promising start under Roberto Mancini and has won five England caps since his move, but has struggled for a regular place at Eastlands.
He has started most of City's Europa League ties, and only failed to appear in four games all season, but is growing frustrated because he has started just four Barclays Premier League games. Mancini has also been critical of the Middlesbrough Academy graduate, putting further strain on their relationship.
In demand: Adam Johnson (left) in action for Manchester City against Juventus in Turin last year
After he scored against Red Bull Salzburg earlier this month, the City manager said: 'Adam must realise he must work and keep it going. I hope he understands I say these things because I believe in him. If he works well he could be a very good player. In three or four years, when I leave City, I hope he will say, "Roberto did a good thing for me."'
Johnson may welcome the chance to move back to the North East, where his parents still live, and help Sunderland's new year push for Europe, but there are obstacles for Bruce to overcome to pull off the double deal.
Premier League clubs can only take two England-based players on loan in a season. With Manchester United striker Danny Welbeck also on loan at Sunderland, Bruce must take Onuoha full time to make another loan deal in the transfer window.
England Under 21 player Welbeck, who scored his fifth Sunderland goal in seven games in Saturday's 1-0 win over Bolton, is still part of Sir Alex Ferguson's long-term plans and Bruce knows his former boss will not sell at this point.
Only on loan: Danny Welbeck scored against Bolton last weekend but is still part of Sir Alex Ferguson's long-term plans at Manchester United
The Sunderland manager, who shares a New Year's Eve birthday with Ferguson, has joked that he will get the United boss drunk on his 50th birthday and try to secure a permanent deal for the 20- year-old, who is ineligible for the Boxing Day meeting between the two sides.
As well as persuading City to do business on both Onuoha and Johnson, Bruce will have to convince Sunderland owner Ellis Short to fund the deals and find a compromise over Johnson's wages.
Bruce is also keeping tabs on Johnson's old friend, Middlesbrough defender David Wheater, who has yet to attract a firm offer from a Premier League club.
Boro fear their former captain could leave on a free in the summer if there are no bids in January.
Newcastle are also willing to make Wheater a summer offer.
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