Leeds have expressed a firm interest in Dyer as they look to secure a second new winger ahead of this evening’s 6pm deadline.
Dyer, 32, is out of favour at Vicarage Road and has not featured in any of Watford’s games this season.
Leeds chairman Massimo Cellino, who recently negotiated a £3m deal with Watford’s Italian owners for Fernando Forestieri, could move in on Dyer in the final hours of the window having sewn up the signing of Botaka last night.
Botaka, a 22-year-old Congo international, will join Leeds on a two-year deal for a fee in the region of £1m.
Dyer possesses more experience than Botaka and has made over 400 appearances in a career which has took him to West Bromwich Albion, Leicester City and MK Dons before Watford.
He joined Watford last summer and played a bit-part role in their promotion to the Premier League before finishing the campaign on loan at Birmingham City.
With the transfer deadline on the horizon, Leeds appear to have ended their interest in Wolverhampton Wanderers’ Rajiv van La Parra but are continuing to monitor Sunderland’s Will Buckley.
Nottingham Forest forward Jamie Paterson has also attracted interest from Elland Road.
Nicky Ajose, meanwhile, could be heading out of Leeds following an approach for him from League One side Coventry City.
The former Manchester United trainee is out of favour at United but has two years remaining on his contract.
Leeds are keen to secure a transfer which covers the cost of paying up his deal.