strongly requested by the UDC, and finally agreed by Berlusconi, although criticised (including by political scientist Giovanni Sartori) for its comeback to proportionalism and its timing, less than one year before general elections. Provision was also included, on the input of Mirko Tremaglia, to ease the vote of Italians resident abroad; paradoxically, Italians abroad proved crucial in securing centre-left victory in 2006 elections. The Union government of Romano Prodi (2006–2008) Romano Prodi, with a centre-left coalition (The Union), won the April 2006 general election by a very narrow margin due to Calderoli new electoral law, although Silvio Berlusconi first refused to acknowledge defeat. Prodi's coalition proved to be extremely frail, as the two-vote margin in the Senate allowed almost any party in the coalition to veto legislation and political views inside the coalition spanned from the left-wing communist parties to the centrist Christian Democrats. In foreign policy, the Prodi II Cabinet continued the engagement in Afghanistan, under UN command, while withdrawing troops from post-invasion Iraq. The major effort of foreign minister Massimo D'Alema concerned the aftermath of the 2006 Lebanon War, being the first to offer troops to the UN for the constitution of the UNIFIL force, and assuming its command in February 2007. Less than a year after he had won the elections, on 21 February 2007, Prodi tendered his resignation to Head of State Giorgio Napolitano after the government was defeated in the Senate by 2 ballots in a vote on foreign policy. On 24 February, President Napolitano invited him to return to office and face a vote of confidence. Major causes of friction inside the coalition were, the 2006 pardon Act (criticised by the right and by the IDV party), a draft bill to establish civil unions (vetoed by Christian Democrats), Italy's continued involvement in Afghanistan (strongly opposed by left-wing parties), and finally the much publicized house-arrest of Clemente Mastella's wife (then a prominent politician at the regional level) over a corruption scandal. Mastella's party, UDEUR, held just enough seats in the Senate that his eventual decision to withdraw its support for the government meant the end of the legislature on 6 February 2008. Mastella, who also resigned from his office as Minister of Justice, cited the lack of personal support from his coalition partners' as one of the reasons behind his decision, together with a proposed reform of the electoral system which would have made it