BRUSSELS (Reuters) - British Prime Minister David Cameron said he was "delighted" with a promise from Polish premier Donald Tusk, newly elected to a top European Union post, to address his demands for reforming the EU to keep Britain in the bloc.
Two months after suffering a severe and very public setback when he failed to block the appointment of another EU leader whom he judged hostile to his reform drive, Cameron was upbeat about the choice of the Polish centre-right leader as head of the European Council, the body representing the 28 EU governments.
Immediately after being appointed by EU leaders at a Brussels summit on Saturday, Tusk held out an olive branch to Britain, saying he was prepared to compromise on British concerns in order to keep the country in the EU.
"I am delighted obviously with what Donald Tusk has said about the importance of reform in the EU and addressing the concerns that Britain has in the EU and I look forward to working with him in the months and the years ahead," Cameron told reporters as he left the meeting early on Sunday.
In the face of eurosceptic sentiment within his own party and the wider British electorate, Cameron has promised to renegotiate Britain's ties with the EU if he is re-elected next year, and then to put the country's continued membership of the EU to a referendum in 2017.
In June, Cameron's bid to block the nomination of former Luxembourg prime minister Jean-Claude Juncker as president of the European Commission, the EU's executive body, failed disastrously, leaving Cameron isolated among his peers.
A downcast Cameron said then that the choice of Juncker, who he viewed as too federalist, was "a serious mistake" that would make it harder for him to keep Britain inside the EU.
ROOM FOR COMPROMISE
Cameron publicly threw his support behind Tusk for the other top EU job this week after receiving assurances that the Polish politician was sympathetic to his plans to reform the EU, which Cameron views as too centralised and bureaucratic.
If he wins reforms, it would give Cameron ammunition to argue that Britain should remain in the EU during campaigning for a referendum on whether to stay in or leave the EU.
Tusk will also chair euro zone summits despite Poland, like Britain, not using the euro single currency.
Tusk suggested there was room for compromise on Cameron's concerns over the abuse of welfare system by jobless migrants across the bloc's borderless labour market. Poles, most of them working, have become one of Britain's biggest immigrant communities since Warsaw joined the EU 10 years ago.
"The European Union, and I personally, will certainly meet the concerns voiced by Britain," Tusk said.
"I am talking about Britain because I am convinced that the future of the European Union will not be in shrinking the EU and no one reasonable can imagine the EU without Britain.
"I, too, cannot imagine such a black scenario.
"I talked about it with David Cameron and I understand many of his attempts, proposals of reform, and I think they are acceptable to reasonable politicians in Europe, also when it comes to a search for a compromise, a common position to eliminate the abuse of the system of the free movement of workers."
The outgoing president of the European Council, Belgian Herman Van Rompuy, listed Britain's place in the EU as one of the three major challenges Tusk will face over the next few years, alongside the stagnating economy and the Ukraine crisis.
Cameron clashed with the European Commission last year after unveiling plans to limit EU migrants' access to welfare in Britain and said he wanted eventually to restrict migrants from poorer EU states relocating to richer ones.
The Commission told Britain last November that EU freedom of movement rules were non-negotiable and that London had to accept them if it wanted to remain in the bloc's single market.
In July, Cameron set out new welfare rules to cut access to social security payments for migrants from the EU.
British opinion polls show immigration is one of voters' biggest concerns, fuelling a rise in eurosceptic sentiment that has helped the anti-EU UK Independence Party (UKIP) draw voters away from Cameron's Conservatives.
Cameron caused outrage in Poland in January with remarks about Polish migrants pocketing British welfare payments. Tusk said at the time he would ask Cameron to explain his comments.
Tusk said then that Poland would veto any changes to EU rules aimed at reducing welfare payments for any particular nationality rather than applying equally to citizens of all EU member states.
(Editing by Alastair Macdonald)