BRUSSELS, Nov 21 (AFP) - The new European Commission team of Portugal's Jose Manuel Barroso faces a number of important challenges after it finally takes office on Monday.

- ECONOMIC REFORMS

Barroso, a former Portuguese prime minister, has made the so-called Lisbon strategy, agreed in 2000, and aimed at making the EU the world's most competitive economy by 2010, the big priority of his mandate.

- CONSTITUTION CONTINGENCY PLAN

The executive will have to work out a contingency plan in case any of the 25 member states reject the European Union constitution. The plan will be different according to who rejects it: a small country, Britain, or one of the founding members like France. If the constitution does finally come into force, it will impose change at the Commission, with the creation of an EU foreign affairs minister, who will become a deputy president of the executive.

- HIGH RISK ACCESSION NEGOTIATIONS WITH TURKEY

The European Commission will have the extremely difficult task of preparing membership negotiations with Turkey, if, as expected, EU leaders give the green light for the opening of talks in December. The Commission will also prepare accession talks with Croatia and for the expected 2007 membership of Romania and Bulgaria.

- NEGOTIATIONS ON THE EUROPEAN BUDGET FOR 2007-2013

The Commission will be a key mediator when haggling between EU member states on the EU's budget for 2007-2013 starts in earnest. The mighty budget currently equals one percent of the EU's gross domestic product, while the Commission wants to raise that to 1.14 percent. Not surprisingly, the stakes will be high, as countries will want to pay as little in, and get as much as possible out.

- LEGISLATION

Among the big pieces of legislation the Commission will have to handle will be negotiations with the European Parliament on a directive on services. The law will force member states to lower barriers to the free provision of services. Also lying ahead is an EU law on the registering and evaluation of chemical products (REACH). Industry is bitterly opposed to the law, while the big industrialised powers -- Germany, France and Britain -- are highly dubious.