ROME, Italy — Silvio Berlusconi, Italy's prime minister for seven of the last 10 years, constantly complains that "hidden powers" and a rigid Constitution, together with closet-Communists from the opposition Democratic Party, hinder his capacity to rule the Bel Paese, trampling the wide majority he received at the polls.

Now, it seems that for years he was looking for enemies in the wrong place. His real political nemesis, Gianfranco Fini, as it turned out, was right their in the midst of his own party.

On July 29, Berlusconi ousted Fini — the charismatic, current speaker of the Lower Chamber of the Italian parliament — from his People of Freedom party, accusing the party co-founder of being “totally incompatible” with its principles. He also contended that Fini was waging a shadow “political opposition” within his own party, trying to administer a “slow death” to it.

He had reason to be worried: 33 lawmakers from the lower house of parliament and 10 from the Senate abandoned the People of Freedom upon Fini's departure, leaving Berlusconi five votes short of a majority in the lower house and with a wafer-thin majority of two votes in the upper house.

Fini has pledged support for Berlusconi on an ad hoc basis, vowing to fight fiercely against proposals that are “unfair or damaging to the wider interest.”

That should prevent the prime minister from pushing through some of his more controversial ideas. He has already been forced to postpone until September the voting on a law which would curb wiretaps that has been criticized by magistrates and journalists alike.

The first "stress test" for this new arrangement came on Wednesday, as parliament voted on a no-confidence motion against Giacomo Caliendo, a junior justice minister under investigation for his alleged role in a secret organization plotting to fix political and judicial appointments. The motion failed after Fini's loyalists abstained in the vote, along with three small centrist parties. In doing so, they avoided direct confrontation with Berlusconi while still firing a warning shot at the government.

Fini seems an unlikely nemesis for Berlusconi. A 58-year-old chain smoker, he is the former head of the post-fascist party Italian Social Movement, born from the ashes of Mussolini's regime in 1946.

He led the Italian Socialist Movement onto a path of modernization, through the acceptance of democratic values and condemnation of anti-Semitism, and eventually re-branded it the National Alliance in 1995.

But all this probably wouldn't have landed him anywhere close to power without Berlusconi's support. It was Berlusconi the media mogul who shortly before entering politics in December 1993 endorsed Fini's run to become mayor of Rome. He failed — but barely, meaning that for the first time since World War II, a post-Fascist had been a credible contestant for an important political role.

In 1994, when Berlusconi became prime minister for the first time, Fini was a key ally and his party was awarded four cabinet posts.

Ever since, he had stood faithfully by Berlusconi's side, becoming deputy prime minister in 2001 and merging his own party with Berlusconi's Forza Italia to form the tycoon's latest political outfit, the People of Freedom, two years ago. He was rewarded with the prestigious role of speaker of the chamber.

How, then, did Fini end up becoming the only person apparently capable of ending Berlusconi's decade long stranglehold on Italian politics?

To those with a keen eye, telling signals have been there for a long time.

In 2003, he called for granting immigrants the right to vote at local elections — something that put him at odds with another key Berlusconi ally, the separatist Northern League. Breaching one of the unwritten laws of mainstream Italian politics, he has also often came out against the Catholic Church on issues ranging from in vitro fertilization to assisted suicide.

In recent months, tensions between the two men have been rising and rising: Fini not only spoke against some of Berlusconi's more controversial ideas — denouncing rampant political corruption in the People of Freedom party and criticizing his allies who have been caught up in judicial investigations — but also accused the Prime Minister of running their party like a monarch and stifling internal debate.

To many, this was just political positioning with an eye to the succession of 73-year-old Berlusconi. But for other commentators, such as Alessandro Campi, a political scientist who is a key adviser to Fini, he is fighting a battle for the “soul” of Italy's center-right majority. The post-fascist leader, Campi believes, is aiming to create a liberal conservative party free from the baggage of Berlusconi's judicial woes.

What will happen next?

According to the Italian press, Berlusconi has threatened a snap election “at the first incident” with Fini's loyalists. Electoral campaigns are what he is best at, but under the Italian Constitution only the President of the Republic can dissolve Parliament.

What is sure is that Berlusconi's break-up with Fini means that he has failed in at least one respect: he hasn't managed to reform Italy's fractional politics, creating a basically two-party system like the American or British one, thus leaving the endless horse-trading a necessary in order to keep coalition governments stable.

In fact, Berlusconi — the former businessman who despises "politicking" — will have to resort to all the arts of old-style politics in order to stay in power.

Editor's note: This story was updated to give the result of a no-confidence motion voted on by the Italian parliament on Aug. 4.