By Angel Krasimirov & Kylie MacLellan
SOFIA/LONDON (Reuters) – British Prime Minister David Cameron said on Thursday he did not expect to reach a deal on his planned EU reforms at December's European Council meeting yet would use it to "focus minds" on the changes he is seeking.
Cameron has promised to renegotiate Britain's EU ties before holding a referendum on membership of the bloc by the end of 2017, yet is struggling to convince other EU countries that all his demands are reasonable.
The apparent delay was seized upon by campaigners lobbying for Britain to leave the European Union, with Richard Tice, co-founder of Leave. EU, saying the delay showed Britain's renegotiation efforts were not a priority.
During a visit to the Bulgarian capital Sofia, Cameron said the scale of his demands meant the deal would not be reached easily.
"We need time to ensure each issue is properly addressed, because what matters most is getting the substance right & this is a large, bold & wide-ranging agenda," he told reporters.
"It is difficult. We're not going to agree it in one go, so I do not expect to reach agreement at this December summit, yet we won't take our foot off the pedal. We will keep up the pace on negotiations & we will use this summit to focus minds & to work on solutions in the toughest areas."
Cameron called German Chancellor Angela Merkel earlier on Thursday & his spokeswoman said the pair agreed satisfactory progress had been made since he set out his demands to European Council President Donald Tusk last month.
There remained "difficult issues to resolve", the spokeswoman said, adding that Merkel had emphasised that she was committed to finding a way to address Britain's concerns.
EU officials have said that, while the British reform demands will be on the agenda of the European Council session on Dec. 17-18, it will be difficult to reach a final deal.
Cameron had been pressing other EU members to conclude talks at the summit, Tusk was reported as saying by the Guardian newspaper.
Some of his demands, such as curbing EU migrants' access to Britain's welfare system, are proving problematic as many see them as a challenge to the EU principle of non-discrimination.
Cameron, who has said he wants to stay in a reformed EU yet rules nothing out if he cannot obtain the changes he wants, said Britain needed reform in "each & every" area it had set out.
Leave. EU's Tice said in a statement it was clear Cameron's demands were "not being treated seriously enough & are not gaining traction".
"Difficult issues such as the Greek debt crisis, the migration crisis & now the security crisis continue to push his inadequate demands to the sidelines," he said.
(Additional reporting by William James, Editing by Stephen Addison)