Article and photo by BBC News
David Cameron press conference PM David Cameron has said "really good progress" has been made at EU summit talks in Brussels but renegotiating UK membership would be "very difficult".
Mr Cameron presented his bid to reform the UK's links with the EU at dinner on the first day of the two-day summit.
The prime minister said hard work would be needed on the four issues for change he put forward at the meeting. European Council president Donald Tusk said the talks represented a "make or break moment".
The main sticking point is Mr Cameron's plans to ban EU migrants from claiming in-work benefits, such as tax credits, for four years.
Mr Cameron said: "We are attempting something very difficult, attempting something that hasn't been tried by another country and that is to renegotiate our position inside this European Union at a time of our choosing, with a mandate of the British people.
"What has happened is we have taken a big step forward for a better deal for Britain. There's still a lot of hard work to be done but there is a path through this to a better deal for Britain."
The prime minister added: "In terms of welfare, no I haven't put any other proposals on the table - I have put my four-year proposal on the table and it remains on the table.
"The commission said that they believed there were solutions - not compromises, solutions. I am confident after tonight that we can find solutions."
Mr Tusk said Mr Cameron set out his position, especially on benefits and free movement. He added that leaders voiced concern but were willing to look for compromises.
"Building on this positive debate we agreed to work together to find solutions in all four baskets raised by Prime Minister Cameron," he said.
German Chancellor Angela Merkel said: "I am optimistic because we all want a compromise. But work on substance needs to be done. Treaty change might be possible. Not now but perhaps later."
French President Francois Hollande said there could be adjustments over Mr Cameron's demands but EU rules and principles must be respected.
European Commission president Jean-Claude Juncker warned that all four of Mr Cameron's demands were difficult, and intensive negotiations were needed before the next summit in February.
He said: "I'd like to warn you of the illusory impression that there are three easy questions and one tricky one.
"There are four tricky questions, each one covers further questions and we have to consider all of those until February."
BBC political editor Laura Kuenssberg says there was no new detail of how the negotiations might conclude, just a pathway forward.
Mr Cameron also wants protection for countries outside the eurozone, measures to boost competitiveness and an exemption for Britain from the drive towards an "ever-closer union". He wants to get a new deal for the UK before putting its membership to an in-out referendum by the end of 2017.
Thursday's discussions over dinner were the first time EU leaders had discussed Mr Cameron's reform proposals in detail.
Also on the agenda at the EU Council meeting was the migrant crisis, climate change and the fight against terrorism.