U.S. Senator John McCain, a Republican Party politician from Arizona who was a member of the U.S. Congress from 1983 until his death in office in 2018, a two-time U.S. presidential candidate, and the nominee of the Republican Party in the 2008 U.S. Presidential election, took positions on many political issues through his public comments, his presidential campaign statements, and his senatorial voting record.

Online, McCain used his Senate web site and his 2008 campaign web site to describe his political positions.

Regarding the general notion of consistency of political positions over time, McCain said in June 2008: "My principles and my practice and my voting record are very clear. Not only from 2000 but 1998 and 1992 and 1986. And you know, it's kind of a favorite tactical ploy now that opponents use, of saying the person has changed. Look, none of my principles or values have changed. Have I changed position on some specific issues because of changed circumstances? I would hope so! I would hope so!" McCain was considered a moderate or centrist at different times in his career such as when he opposed the planned implementation of the Bush tax cuts in 2004. It was often reported that McCain had grown more conservative throughout his tenure in the Senate, according to various studies. During Barack Obama's presidency, McCain was one of five Republicans most likely to vote in line with President Obama's position on legislation; he voted with Obama's position more than half the time in 2013.

The non-partisan National Journal published an analysis of members of Congress in which it gave McCain a composite ideological rating of 60% conservative and 40% liberal in 2013. On The Issues, a non-partisan and non-profit organization, identifies McCain as a "Libertarian Conservative". In 2017, the American Conservative Union gave McCain a 57% grade based on their positions and the ACU gives him an 81% lifetime conservative score; the American Civil Liberties Union, which focuses on civil rights and liberties, gave McCain a 53% rating in 2014. In 2013, Americans for Democratic Action, a progressive political action committee, gave him a rating of 20% in line with their positions.

He was a member of Republican Main Street Partnership, a Republican group which presents what it describes as centrist Republican solutions in politics.

McCain's 2006 rating by The Almanac of American Politics (2008) on Economic Policy was 64% conservative, 35% liberal (52% conservative, 47% liberal in 2005). McCain fleshed out the main points of his economic plan in an April 15, 2008 speech at Carnegie Mellon University in Pennsylvania. In summary, McCain would make the Bush tax cuts permanent instead of letting them expire, he would eliminate the Alternative Minimum Tax in order to assist the middle-class, he would double the personal exemption for dependents, reduce the corporate tax rate, and offer a new research and development tax credit. At the same time, he pledges to eliminate pork-barrel spending, freeze nondefense discretionary spending for a year or more, and reduce Medicare growth. He was also opposed to extravagant salaries and severance deals of corporate CEOs. In 2013, the National Journal gave McCain an economic rating of 61% conservative and 38% liberal.

While McCain had historically opposed tax cuts in favor of deficit reduction, he supported tax cuts as part of his presidential campaign. He said that he would reduce government spending to make up for the tax cuts.

McCain had declined to sign the pledge of the group Americans for Tax Reform to not add any new taxes or increase existing taxes. However, after he lost the presidential election in 2008, McCain became a signer of Americans for Tax Reform's Taxpayer Protection Pledge. In 2002, Sen. McCain was one of only two Republicans to twice vote against the permanent repeal of the Estate Tax, and has recently stated opposition to a permanent repeal of the Estate Tax. McCain was one of two Republicans who voted against Bush's tax cuts in 2001. He opposed accelerating the cuts in 2003, saying that he was not in favor of cutting taxes during a time of war. In 2004 McCain appeared on Meet The Press with Tim Russert where he was asked about his opposition to the Bush tax cuts. McCain explained himself by saying, "I voted against the tax cuts because of the disproportional amount that went to the wealthiest Americans. I would clearly support not extending those tax cuts in order to help address the deficit." However, McCain supported the Bush tax cut extension in May 2006, and January 2008 he told Russert that he favors making those tax cuts permanent to prevent an increase in taxes while the economy was "shaky." He also said that his tax proposal would focus more on middle-income Americans than on the wealthy.