By Elizabeth Pineau and Kylie MacLellan
PARIS/LONDON (Reuters) - David Cameron embarks on a final push for support in Europe for a deal to help keep Britain in the EU when he meets French President Francois Hollande on Monday and then leaders of a wary European Parliament in Brussels.
Two weeks after a draft accord won initial backing from fellow national leaders who will try to iron out remaining differences with the British prime minister at a summit on Thursday, Tuesday's meeting with EU lawmakers highlights some of the risks of political turbulence before a British referendum.
Not only was a plan to meet leaders of all the European Parliament's party blocs canceled -- allowing Cameron to avoid a confrontation with his euroskeptic arch critic Nigel Farage -- but the need for the assembly's approval of key elements raised questions about how binding any summit agreement will be.
Speaking before Cameron begins his last planned pre-summit trip at a Paris meeting with Hollande, his spokeswoman rebuffed questions in London about the extent to which the European Parliament could later block reforms agreed by the leaders after Britons vote in the referendum, possibly in June.
Insisting that senior parliamentarians have indicated their general support, and refusing to speculate on the "hypothetical" situation where the legislature refuses to pass laws that the leaders agree on, the spokeswoman said: "We have been very clear this is a legally binding, irreversible decision."
Leading members of parliament have been involved in negotiations and say they are willing to work on legislation to, for example, help Britain discriminate against EU workers on benefits to discourage immigration.
But the 750-seat chamber is dominated by supporters of closer European integration, jealous of their powers and little given to voting discipline within their trans-national parties -- creating a risk of delay or amendment to legislation that Farage, a seasoned anti-EU campaigner was quick to highlight.
In a statement describing Conservative leader Cameron as "gutless" for choosing to meet only leaders of the three main parties rather than all eight, including himself, Farage said:
"He knows that not only is his deal pitiful but that ... I would be able to expose the fact that even if he wins the referendum, the parliament will veto its terms."
If the 28 national leaders agree to a deal on the basis of a draft brokered by summit chairman Donald Tusk, Cameron is expected to call the referendum and campaign to stay in a "reformed European Union". The precise legal form of the accord is still under discussion but EU and British officials say it would have the force of a binding international treaty.
It would only come into force, however, after British voters backed continued EU membership. Only then would the European Parliament consider legislation, still to be drafted by the EU executive European Commission, to put some changes into law.
Cameron has said Tusk's current offer will give Britain the ability to reduce immigration from the rest of the EU, protect its sterling-based finance industry from being disadvantaged by the majority of EU states in the euro zone and ensure Britain's right not to be drawn deeper into a political union in Europe.
A diplomatic source said the British do not want any retreat from Tusk's proposals as Cameron has to have a deal he can sell to both the public, and the already unimpressed euroskeptics in his own Conservative Party.
After himself meeting Hollande in Paris on Monday, Tusk said he hoped for a deal in Brussels at the end of the week.
The French are seeking to limit any British right to interfere in euro zone decisions, and ensure Britain commits to allowing further integration of the euro area, the source said.
France secured some amendments last week that Paris said were needed to ensure that efforts to balance the euro zone's "ins" and "outs" did not give the City of London an unfair edge.
An EU source said Tusk and Hollande had gone through all the outstanding political issues with a focus on finding solutions to the French concerns on that issue. Progress had been made but there was still some work to be done.
(Additional reporting by Paul Taylor in Paris and Jan Strupczewski, Alastair Macdonald, Gabriela Baczynska, and Tom Koerkemeier in Brussels; Writing by Alastair Macdonald; editing by John Stonestreet)