From Pew Research Center:
Independents often are portrayed as political free agents with the potential to alleviate the nation's rigid partisan divisions. Yet the reality is that most independents are not all that "independent" politically. And the small share of Americans who are truly independent – less than 10% of the public has no partisan leaning – stand out for their low level of interest in politics.
Among the public overall, 38% describe themselves as independents, while 31% are Democrats and 26% call themselves Republicans, according to Pew Research Center surveys conducted in 2018. These shares have changed only modestly in recent years, but the proportion of independents is higher than it was from 2000-2008, when no more than about a third of the public identified as independents. (For more on partisan identification over time, see the 2018 report "Wide Gender Gap, Growing Educational Divide in Voters' Party Identification.")
An overwhelming majority of independents (81%) continue to "lean" toward either the Republican Party or the Democratic Party. Among the public overall, 17% are Democratic-leaning independents, while 13% lean toward the Republican Party. Just 7% of Americans decline to lean toward a party, a share that has changed little in recent years. This is a long-standing dynamic that has been the subject of past analyses, both by Pew Research Center and others...