John McCain in the context of "Barack Obama"

George W. Bush's tenure as the 43rd president of the United States began with his first inauguration on January 20, 2001, and ended on January 20, 2009. Bush, a Republican from Texas, took office after defeating the Democratic incumbent vice president Al Gore in the 2000 presidential election. Four years later, he won re-election in the 2004 presidential election, after defeating the Democratic nominee John Kerry. Alongside Bush's presidency, the Republican Party also held their majorities in the House of Representatives and the Senate during the 108th and 109th U.S. Congresses following the 2002 and 2004 elections, thereby attained an overall federal government trifecta. Bush was constitutionally limited to two terms and was succeeded by Democrat Barack Obama, who won the 2008 presidential election against Bush's preferred succcessor, John McCain. He is the eldest son of the 41st president, George H. W. Bush.

A decisive event reshaping Bush's administration were the terrorist attacks on September 11, 2001. In its aftermath, Congress created the Department of Homeland Security and Bush declared a global war on terrorism. He ordered an invasion of Afghanistan in an effort to overthrow the Taliban, destroy al-Qaeda, and capture Osama bin Laden. He also signed the controversial Patriot Act in order to authorize surveillance of suspected terrorists. In 2003, Bush ordered an invasion of Iraq, alleging that the Saddam Hussein regime possessed weapons of mass destruction. Intense criticism came when neither WMD stockpiles nor evidence of an operational relationship with al-Qaeda were found. Before 9/11, Bush had pushed through a $1.3 trillion tax cut program and the No Child Left Behind Act, a major education bill. He also pushed for socially conservative efforts, such as the Partial-Birth Abortion Ban Act and faith-based welfare initiatives. Also in 2003, he signed the Medicare Prescription Drug, Improvement, and Modernization Act, which created Medicare Part D.

In early 2007, Ron Paul, a congressman from Texas, announced his candidacy for the Republican Party's nomination for president of the United States in the 2008 election. Initial opinion polls during the first three quarters of 2007 showed him consistently receiving support from 3% or less of those polled. In 2008, Paul's support among Republican voters remained in the single digits, and well behind front-runner John McCain.

During the fourth quarter of 2007, Paul was the most successful Republican fundraiser, bringing in approximately $20 million. He also received the most money from the armed services of any candidate in the fourth quarter. His campaign set two fund-raising records: the largest single-day donation total among Republican candidates and twice receiving the most money received through the internet in a single day by any presidential candidate in American history. Paul's run for president is also noted for its grassroots social networking, facilitated by the Internet. Paul's enthusiastic supporters were noted by the media, who called them "Paulites". Paul received most of his contributions from individuals, at ninety-seven percent, compared to other candidates.

Presidential elections were held in the United States on November 7, 2000. The Republican ticket of Texas governor George W. Bush—the eldest son of the 41st president George H. W. Bush—and former secretary of defense Dick Cheney very narrowly defeated the Democratic ticket of incumbent vice president Al Gore and Connecticut senator Joe Lieberman. It was the fourth of five U.S. presidential elections, and the first since 1888, in which the winning candidate lost the popular vote, and is considered one of the closest U.S. presidential elections in history, with long-standing controversy about the result.

Incumbent Democratic president Bill Clinton was ineligible to seek a third term because of term limits established by the 22nd Amendment. Incumbent vice president Gore easily secured the Democratic nomination, defeating former New Jersey senator Bill Bradley in the primaries. He selected Connecticut senator Joe Lieberman as his running mate. Bush was seen as the early favorite for the Republican nomination, and after a contentious primary battle with Arizona senator John McCain and others, he secured the nomination by Super Tuesday. He selected former secretary of defense Dick Cheney as his running mate.

Christopher Hitchens (13 April 1949 – 15 December 2011) was a British and American author, polemicist, debater and journalist who in his youth took part in demonstrations against the Vietnam War, joined organisations such as the International Socialists while at university and began to identify as a socialist. However, after 9/11 he no longer regarded himself as a socialist and his political thinking became largely dominated by the issue of defending civilization from terrorists and against the totalitarian regimes that protect them. Hitchens nonetheless continued to identify as a Marxist, endorsing the materialist conception of history, but believed that Karl Marx had underestimated the revolutionary nature of capitalism. He sympathized with libertarian ideals of limited state interference, but considered libertarianism not to be a viable system. In the 2000 U.S. presidential election, he supported the Green Party candidate Ralph Nader. After 9/11, Hitchens advocated the invasion of Iraq. In the 2004 election, he very slightly favored the incumbent Republican President George W. Bush or was neutral and in 2008 he favored the Democratic candidate Barack Obama over John McCain despite being critical of both of them.

Barack Obama's tenure as the 44th president of the United States began with his first inauguration on January 20, 2009, and ended on January 20, 2017. Obama, a Democrat from Illinois, took office after defeating the Republican nominee John McCain in the 2008 presidential election. Four years later, he won re-election in the 2012 presidential election, after defeating the Republican nominee Mitt Romney. Alongside Obama's presidency, the Democratic Party also held their majorities in the House of Representatives during the 111th U.S. Congress following the 2008 elections, thereby attained an overall federal government trifecta. Obama is the first African American president, the first multiracial president, the first non-white president, and the first president born in Hawaii. Obama was constitutionally limited to two terms (the second re-elected Democrat President to be so) and was succeeded by Republican Donald Trump, who won the 2016 presidential election against Obama's preferred successor, Hillary Clinton. Historians and political scientists rank him among the upper tier in historical rankings of American presidents.

Obama's accomplishments during the first 100 days of his presidency included signing the Lilly Ledbetter Fair Pay Act of 2009 relaxing the statute of limitations for equal-pay lawsuits; signing into law the expanded Children's Health Insurance Program (S-CHIP); winning approval of a congressional budget resolution that put Congress on record as dedicated to dealing with major health care reform legislation in 2009; implementing new ethics guidelines designed to significantly curtail the influence of lobbyists on the executive branch; breaking from the Bush administration on a number of policy fronts, except for Iraq, in which he followed through on Bush's Iraq withdrawal of US troops; supporting the UN declaration on sexual orientation and gender identity; and lifting the 7½-year ban on federal funding for embryonic stem cell research. Obama also ordered the closure of the Guantanamo Bay detention camp, in Cuba, though it remains open. He lifted some travel and money restrictions to the island.

Presidential elections were held in the United States on November 4, 2008. The Democratic ticket of Barack Obama, the junior senator from Illinois, and Joe Biden, the senior senator from Delaware, defeated the Republican ticket of John McCain, the senior senator from Arizona, and Sarah Palin, the governor of Alaska. Obama became the first African American to be elected to the presidency.

Incumbent Republican president George W. Bush was ineligible to pursue a third term due to the term limits established by the Twenty-second Amendment; this was the first election since 1952 in which neither the incumbent president nor vice president was on the ballot, and the first since 1928 in which neither ran for the nomination. McCain secured the Republican nomination by March 2008, defeating his main challengers Mitt Romney and Mike Huckabee, and selected Palin as his running mate. The Democratic primaries were marked by a sharp contest between Obama and the initial front-runner, former first lady and Senator Hillary Clinton, as well as other challengers who dropped out before most of the primaries were held, including Senators John Edwards and Joe Biden. Clinton's victory in the New Hampshire primary made her the first woman to win a major party's presidential primary. After a long primary season, Obama narrowly secured the Democratic nomination in June 2008 and selected Biden as his running mate.