Well-placed sources said the bank was looking for a UK-based public affairs firm with a strong grasp of EU policy. The Spanish banking group has been in contact with a handful of agencies and has drawn up a shortlist.
The bank currently retains Hanover in the UK but the agency's brief also covers some other EU member states. Santander also retains Connect Communications for monitoring work, and has recently used Four Communications for public affairs.
Santander declined to say whether Hanover, Connect and Four would be affected.
The search for an agency is being overseen by Emmeline Owne, head of government relations and public policy at Santander UK and Conservative candidate for Neath in the 2010 general election.
She said: 'This repitch is no comment on the performance of any incumbent agency. The selected agencies will be notified shortly.'
Key issues for the new agency could include the EU regulatory reform agenda and its influence over the shape of banking competition.
This week it was reported that Santander is set to recruit as many as 6,000 people in the UK over the next year or two. That would be in addition to the 5,000 frontline employees it is inheriting from Royal Bank of Scotland as part of last month's acquisition of 318 branches.