MADRID (Reuters) - The Spanish government is committed to seeking a joint response with other political parties to the  pro-independence challenge  in Catalonia after Sunday s outlawed referendum, a government statement said on Monday. In meetings with leaders of two other parties, the Socialists and the centrist Ciudadanos, Spanish Prime Minister Mariano Rajoy had shown his readiness to study proposals put forward by other parties to respond to the Catalan issue, the statement said. In conversations with European leaders on Monday, Rajoy thanked them for their support for Spain s constitutional order, the statement said. 