Question: Marco Rubio presidential campaign, 2016 declared he was running for president approximately three weeks after this fellow republican who has served  as the junior United States Senator from Texas since what year
Context: The 2016 presidential campaign of Ted Cruz, the junior United States Senator from Texas, was announced on March 23, 2015.  He was a candidate for the Republican Party's 2016 presidential nomination and won the second-most state contests and delegates.  Cruz themed his campaign around being an outsider and a strict conservative.  In the crowded early field, he chose not to directly confront the leading candidate, Donald Trump, who was also viewed as an outsider candidate.  His cordial and sympathetic tone towards Trump contrasted with the more critical approach of rivals such as Jeb Bush, Marco Rubio, and Rand Paul. The 2016 presidential campaign of Bernie Sanders, the junior United States Senator and former Representative from Vermont, began with an informal announcement on April 30, 2015, and a formal announcement that he planned to seek the Democratic Party's nomination for President of the United States on May 26, 2015, in Burlington, Vermont.  Sanders had been considered a potential candidate for president since at least September 2014.  Though he had previously run as an independent, he routinely caucused with the Democratic Party, as many of his views align with Democrats.  Running as a Democrat made it easier to participate in debates and get his name on state ballots. Marco Rubio is a Republican politician in the United States.  He is a United States Senator from Florida, and was a candidate for the Republican nomination for president of the United States in the 2016 election. The 2016 presidential campaign of Marco Rubio, the junior United States Senator from Florida, and former Speaker of the Florida House of Representatives, was formally announced on April 13, 2015, at an event at the Freedom Tower in Downtown Miami.  Early polling showed Rubio, who was considered a potential candidate for Vice President by Republican presidential nominee Mitt Romney in 2012, as a frontrunner candidate for the Republican nomination for President of the United States in 2016 since at least the end of the 2012 election.  Rubio was the second Cuban American to run for President of the United States, declaring approximately three weeks after fellow Republican Ted Cruz.  He suspended his campaign on March 15, 2016, after finishing second in the primary for Florida, his home state.  Turning 45 in 2016, Rubio would've been the third youngest president to take office, the others being Theodore Roosevelt and John F. Kennedy, who took office at ages 42 and 43 respectively.  Rubio would've also been the first president of Latin American culture, as he was born to Cuban parents, as well as the first Florida native to become president. Jeanette Christina Dousdebes Rubio (born December 5, 1973) is the wife of United States Senator and 2016 presidential candidate Marco Rubio. George Seay is a Dallas, Texas-based businessman, co-founder and Chairman of Annandale Capital, and conservative political leader.  Seay previously served as Texas finance chairman for Texas Governor Rick Perry’s 2012 Presidential campaign, and is a current senior adviser to Marco Rubio’s 2016 Presidential campaign.  Seay is a 7th generation Texan and the grandson of Bill Clements, who served as the first Republican governor of Texas since Reconstruction.  He serves on numerous boards and philanthropic groups, including The University of Texas McCombs School of Business Advisory Board, The Clements Center for National Security, 7th Generation Foundation, New Covenant Foundation, Hope Through Healing Hands and the Southwestern Medical Foundation. Wayne Lee Berman is an American businessman and former lobbyist.  He currently works for the Blackstone Group.  He was formerly the chairman of Ogilvy Government Relations, a division of Ogilvy & Mather.  Berman is considered a key figure in Republican political advocacy who served as a senior advisor on the 2000 and 2004 Bush-Cheney campaigns, Finance Chairman of the 2008 John McCain presidential campaign, and Chairman of Marco Rubio's 2016 presidential campaign. Lanhee J. Chen ( ; ; born July 4, 1978) is an American policy expert, academic, and political commentator.  Chen currently serves as the David and Diane Steffy Research Fellow at the Hoover Institution, Director of Domestic Policy Studies and Lecturer in the Public Policy Program at Stanford University, and Lecturer in Law at Stanford Law School.  He is also counsel at the law firm Arent Fox LLP.  Chen was a senior adviser to the 2016 presidential campaign of Senator Marco Rubio. Rafael Edward Cruz ( ; born December 22, 1970) is an American politician and attorney who has served as the junior United States Senator from Texas since 2013.  He was a candidate for the Republican nomination for President of the United States in the 2016 election. The 2008 presidential campaign of Barack Obama, then junior United States Senator from Illinois, was announced on February 10, 2007 in Springfield, Illinois.  After winning a majority of delegates in the Democratic primaries of 2008, on August 23, leading up to the convention, the campaign announced that Senator Joe Biden of Delaware would be the Vice Presidential nominee.  At the 2008 Democratic National Convention on August 27, Barack Obama was formally selected as the Democratic Party nominee for President of the United States in 2008.  He was the first African American in history to be nominated on a major party ticket.
Answer: 2013