Question: Émile Cottin attempted to assassinate the leader of which party?

Context paragraphs:
1995 Vallecas bombing: ETA had previously placed car bombs in Madrid, the deadliest being the Plaza República Dominicana bombing in July 1986, which had killed 12 Civil Guards.  The Vallecas attack was the third of 1995.  Earlier in the year, ETA had unsuccessfully attempted to assassinate José María Aznar, head of the People's Party and Leader of the Opposition, who had escaped death due to protection offered by his armoured car.  In the second attack in June, ETA had killed a police officer, Jesus Robello.  The Vallecas attack came just four days after a meeting of European Union heads of state had taken place in Madrid, marking the end of the Spanish Presidency of the EU.

Georges Clemenceau: Georges Benjamin Clemenceau (] ; 28 September 1841 – 24 November 1929) was a French politician, physician, and journalist who was Prime Minister of France during the First World War.  A leader of the Radical Party, he played a central role in the politics of the French Third Republic.

Émile Cottin: Louis Émile Cottin (March 14, 1896 – October 8, 1936, nicknamed "Milou") was a French militant anarchist who is best known for the attempted assassination of Georges Clemenceau.

Izola Curry: Izola Curry ( Ware; June 14, 1916 – March 7, 2015) was an African American woman who attempted to assassinate the civil rights leader Martin Luther King, Jr. She stabbed King with a letter opener at a Harlem book signing on September 20, 1958, during the Harlem civil rights movement of the late 1950s and early 1960s.  King survived Curry's attempt, and forgave her, but was killed less than ten years later in an unrelated incident.

Gopinath Saha: Gopinath Saha (1906-1924) was a Bengali activist for Indian independence (from British rule) and member of the Hindustan Republican Association.  On 12 January 1924, he attempted to assassinate Charles Tegart, a leader in the fight against revolutionary movements and the then head of the Detective Department of Calcutta Police.  Saha's attempt failed as he erroneously killed Ernest Day, a white civilian who had gone there on official business.  Saha was arrested, tried and, in March 1924, hanged.

Daniel Phillips Upham: Daniel Phillips Upham (more commonly known as D.P. Upham; December 30, 1832 – November 18, 1882) was an American politician, businessman, plantation owner, and Arkansas State Militia commander following the U.S. Civil War.  He is best known for his effective and brutal acts as the leader of a successful militia campaign against the Ku Klux Klan.  These acts began after the Klan attempted to assassinate him on October 2, 1868.  Later that year, Upham was designated a brigadier general and commanded a force that eventually numbered over 1,000 men.

Viktor Ilyin: Viktor Ivanovich Ilyin (Russian: Ви́ктор Ива́нович Ильи́н; born 26 December 1947) was a deserter from the Soviet Army, at the rank of second lieutenant, who attempted to assassinate the Soviet leader, Leonid Brezhnev on the 22nd of January 1969 in Moscow.

Führer Headquarters: The "Führer" Headquarters ("Führerhauptquartiere" in German), abbreviated FHQ, is a common name for a number of official headquarters used by the Nazi leader Adolf Hitler and various German commanders and officials throughout Europe during the Second World War.  Perhaps the most widely known headquarters was the "Führerbunker" in Berlin, Germany, where Hitler committed suicide on 30 April 1945.  Other notable headquarters are the "Wolfsschanze" (Wolf's Lair) in East Prussia, where Claus von Stauffenberg in league with other conspirators attempted to assassinate Hitler on 20 July 1944, and Hitler's private home, the "Berghof", at Obersalzberg near Berchtesgaden, where he frequently met with prominent foreign and domestic officials.

20 July plot: On 20 July 1944, Claus von Stauffenberg and other conspirators attempted to assassinate Adolf Hitler, Führer of Nazi Germany, inside his Wolf's Lair field headquarters near Rastenburg, East Prussia.  The name Operation Valkyrie, originally referring to part of the conspiracy, has become associated with the entire event.  The apparent aim of the assassination attempt was to wrest political control of Germany and its armed forces from the Nazi Party (including the SS) and to make peace with the western Allies as soon as possible.  The underlying desire of many of the high-ranking Wehrmacht officers involved was apparently to show the world that not all Germans were like Hitler and the Nazi Party.  The details of the conspirators' peace initiatives remain unknown, but they likely would have included unrealistic demands for the confirmation of Germany's extensive annexations of European territory.

Oscar Collazo: Oscar Collazo (January 20, 1914 – February 21, 1994) was one of two Puerto Rican militants of the Nationalist Party who on November 1, 1950, attempted to assassinate U.S. President Harry S. Truman in Washington, DC.  He had been living in New York City after growing up in Puerto Rico.

Supporting paragraphs: Émile Cottin Georges Clemenceau
Answer: the Radical Party