United are hoping to receive a response from Richardson in the next 48 hours after moving to negotiate revised terms with their out-of-contract captain, but manager Simon Grayson is prepared for the possibility that the player will walk away from Elland Road this summer.

The 26-year-old – United's longest serving player – is a free agent after almost a decade with Leeds, and Grayson should learn this week whether he plans to remain with the club for the 2009-10 campaign.

Richardson began last season as Leeds' first-choice right-back before tearing a thigh muscle and losing his place to Jonathan Douglas.

United have already released Douglas and will find themselves without a right-sided defender if they fail to agree terms with Richardson.

His agent, Alex Black, was planning to clarify Richardson's intentions this week but United have alternative plans in place should he opt for a transfer elsewhere, and Holdsworth and Whing are among the players being considered as potential replacements.

Holdsworth is available on a free transfer after failing to agree a new deal with Huddersfield Town and Brighton defender Whing is out of contract at the Withdean Stadium.

Whing has been offered a new two-year deal by Albion but he has not replied to their proposal and Brighton manager Russell Slade has already moved to identify alternative options for the right side of his defence, an indication of the doubt over Whing's future.

The 24-year-old is a former Coventry City trainee who made more than 100 appearances for the Midlands club before leaving to join Brighton on a permanent transfer two years ago.

Holdsworth came through Huddersfield's academy and featured in over 200 first-team matches, but Town boss Lee Clark was unable to persuade him to take up a fresh contract at the Galpharm.

Richardson, meanwhile, would become the third senior player to leave if he declines their offer, following Douglas and David Lucas out of Elland Road.

Douglas and Lucas were told they were free to move on at the end of their contracts shortly after the end of the 2008-09 season.

A new striker remains high on Grayson's list of priorities with Jermaine Beckford expected to leave before the start of next term.

Grayson has been strongly linked with former Leeds striker David Healy and he is also monitoring Sheffield United's Billy Sharp and Coventry City's Michael Mifsud.