Story Highlights 42% identify as independents, 29% as Democrats, 26% as Republicans

Independent identification at least 40% for fifth consecutive year

Democrats maintain edge over GOP in party identification and leaning

PRINCETON, N.J. -- In 2015, for the fifth consecutive year, at least four in 10 U.S. adults identified as political independents. The 42% identifying as independents in 2015 was down slightly from the record 43% in 2014. This elevated percentage of political independents leaves Democratic (29%) and Republican (26%) identification at or near recent low points, with the modest Democratic advantage roughly where it has been over the past five years.

Since 1988, when Gallup routinely began conducting polls by telephone, there have been many years in which more Americans have identified as independents than as Republicans or Democrats. But the percentage of independents did not reach 40% until 2011, and it has stayed at or above that level for the past five years.

As a consequence, the percentage of U.S. adults identifying as Democrats is now at the lowest point in the past 27 years, down from the prior low of 30% in 2014. Gallup's shift from in-person to telephone interviewing in 1988 complicates the ability to directly compare party identification data collected between the two methods. However, Gallup data from 1951-1987 collected in person never found a yearly average Democratic identification less than 37%, making it safe to conclude that the current 29% is also the low point in Gallup polling history.

The percentage of Republicans is now just one point above its recent low of 25% in 2013. Before 1988, there were several years when the average percentage of Republican identifiers in Gallup polls was lower than 25%.

The rise in political independence is likely related to Americans' frustration with party gridlock in the federal government. In the past several years, dissatisfaction with the government has ranked among the leading issues when U.S. adults are asked to name the most important problem facing the U.S., and was the most frequently mentioned problem in 2014 and 2015. Also, Americans' favorable ratings of each party are on the lower end of what Gallup has measured over the past few decades.

Democrats Maintain Edge When Independents' Leanings Are Factored In

Although political independents lack a strong enough attachment to either party to say they identify as a Republican or a Democrat, most are inclined to favor one party over the other and generally vote that way. After initially asking Americans if they identify as a Republican, a Democrat or an independent, Gallup then probes independents as to whether they lean toward the Republican or the Democratic Party. The combined percentages of party identifiers and leaners give a sense of the relative strength of the two major parties in the U.S., because in most elections, voters are asked to choose a candidate from one of the two parties.

Last year, in addition to the 29% of Americans who identified as Democrats, another 16% said they were independents but leaned toward the Democratic Party, for a combined total of 45% Democrats and Democratic leaners among the U.S. population. Likewise, 26% of Americans identified as Republicans and an additional 16% identified as independents but leaned toward the Republican Party, for a combined total of 42% Republicans and Republican leaners.

That three-percentage-point Democratic advantage matches what the party enjoyed in 2014, but is down from 2012 and 2013. The high point in Democratic strength was in 2008, a time when President George W. Bush was highly unpopular in the midst of the prolonged Iraq war and the emerging economic recession. That year, Democrats had a 12-point advantage in party identification and leaning.

Democrats have had at least a slight advantage nearly every year since Gallup began consistently measuring party leanings in 1991. That initial year -- when President George H.W. Bush led the successful Persian Gulf War effort -- is the only time Republicans held an advantage in party affiliation. In four other years -- 2002, 2003, 2010 and 2011 -- the parties were essentially even.

Implications

Americans' attachment to the two major political parties in recent years is arguably the weakest Gallup has recorded since the advent of its polls. The percentage of U.S. adults identifying as political independents has recently reached levels never seen before. As a result, a new low of 29% of Americans identify as Democrats, and the percentage of Republican identifiers is on the low end of what Gallup has measured historically.

Given that 2016 is a presidential election year, and the percentage of independents usually declines in years when Americans are choosing a president, both parties have an opportunity to win back some of their lost support. But doing so partly depends on how appealing the parties' and their presidential candidates' messages prove to be.

Even if the parties win back some support, they still will probably be competing among an electorate that has a historically high percentage of voters who do not identify with either major party. And the lack of strong attachment to the parties could make candidate-specific factors, as opposed to party loyalty, a greater consideration for voters in choosing a president in this year's election than they have been in past elections.

Historical data are available in Gallup Analytics.

Survey Methods

Results for this Gallup poll are based on combined data from telephone interviews conducted throughout 2015, with a random sample of 12,137 adults, aged 18 and older, living in all 50 U.S. states and the District of Columbia. For results based on the total sample of national adults, the margin of sampling error is ±1 percentage point at the 95% confidence level. All reported margins of sampling error include computed design effects for weighting.

Each sample of national adults includes a minimum quota of 60% cellphone respondents and 40% landline respondents, with additional minimum quotas by time zone within region. Landline and cellular telephone numbers are selected using random-digit-dial methods.

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