Hodgson revealed ealier week that he had identified two "major" players that he wanted to chairman Jeremy Peace, with a new goalkeeper and a new striker top of his shopping list.
The Baggies had been keeping tabs on West Ham stopper Robert Green and are believed to be preparing a bid for Reading hitman Shane Long.
But a development at St Andrew's has bumped Foster to the top of the list, with cash-strapped Blues revealing they would be happy to loan Foster out for the season ahead of a possible £4million permanent deal.
The Carling Cup winners are counting the cost of relegation from the Premier League and are looking to get the 28-year-old off their wage bill.
That has made Foster Hodgson's top goalkeeping target, with the Baggies boss telling the Express & Star: "I am aware of our interest in Ben Foster but I am not aware of how far down the line we are with our negotiations with Birmingham, so I can't make any comments on that.
"But Ben Foster is a goalkeeper who interests us and, if we can get him to West Bromwich Albion on loan or on a permanent deal, that would be something we would be very happy about."
The Baggies are also believed to have held talks with former England midfielder Owen Hargreaves over a possible pay-as-you-play deal in the US, with further talks pencilled in for next week.