Above: The Italian politician representing expatriate Italians, Marco Fedi of the Partito Democratico, speaks to Brian Thomson on the deadlock.
Pietro Grasso was elected to head the Senate and Laura Boldrini as president of the Chamber of Deputies on Saturday.
Coalition talks would now start on Wednesday, President Giorgio Napolitano said.
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Boldrini, a human rights activist who formerly worked for the UN refugee agency (UNHCR), is a member of the Left, Ecology and Freedom (SEL) party.
Grasso is a former top anti-mafia prosecutor and a member of the Democratic Party (PD), the biggest faction in the centre-left alliance that won the February 24-25 elections by a whisker.
Both are first-time members of parliament.
Boldrini's election was expected, since the centre-left has a clear majority in the Chamber. In the Senate, where no coalition has overall control, Grasso prevailed thanks to abstentions from other parties.
However, centre-left leader Pier Luigi Bersani remains 35 seats short of the majority threshold in the Senate, 158. To form a government, he needs support from either the protest Five Star Movement (M5S), or from conservatives led by Silvio Berlusconi.
Bersani has tried to woo the M5S, but has so far been rebuffed, while he has ruled out striking an alliance with Berlusconi, a scandal-tainted former premier. This leaves no obvious way to form a ruling coalition.
A centrist grouping led by outgoing premier Mario Monti has also been elected to parliament, but it did not win enough seats to be able to act as kingmaker.
Napolitano has urged politicians to be ready for compromise in order to break the political deadlock, which risks leaving the eurozone's third-largest economy rudderless for a prolonged period, despite the urgent need for reforms to tackle a severe recession.
However, financial markets have, for the moment, remained relatively calm.
If no ruling majority can be formed in coming weeks, new elections may be called, possible as early as in June.
However, this cannot happen until the newly elected parliament votes on a successor to Napolitano, whose term ends in May.
