Last year, 42% of Americans, on average, identified as political independents, erasing the decline to 39% seen in the 2016 presidential election year. Independent identification is just one percentage point below the high of 43% in 2014. Twenty-nine percent of Americans identify themselves as Democrats and 27% as Republicans. . . . [T]he three-point increase in the proportion of independents in 2017 is larger than what Gallup typically has seen in the year after a presidential election.

Democrats aren’t doing that well either, but they’ve benefited slightly from the drop in GOP identification:

Most people who initially identify as independents will express a “leaning” toward one of the major parties if probed. Gallup has asked independents for their party leanings consistently since 1991. In addition to the 29% of Americans who identify as Democrats, another 18% initially identify as independents but when asked say they lean toward the Democratic Party, resulting in a combined 47% of Democratic identifiers and leaners. Meanwhile, 42% of Americans identify as Republicans (27%) or are Republican-leaning independents (15%).
The five-point Democratic advantage in this combined measure of party affiliation was the same in 2017 as in 2016, but higher than the three-point Democratic leads in 2014 and 2015. Since 1991, the average has been a five-point Democratic edge.

With this in mind, Trump’s poll numbers look much more daunting for him and the GOP. He continues to get about 80 percent of the GOP vote (27 percent of the electorate). But that amounts to a meager 21.6 percent of the electorate as a whole. By playing to his narrow base, pushing highly unpopular measures (the latest being deporting more than 200,000 El Salvadorans who are legally here), demonstrating abject contempt for our democratic system and pushing through a highly unpopular tax bill, Trump is turning off the vast majority of voters. Those Republicans who now cling ever closer to Trump are only compounding their electoral problems.

As for Democrats, they’ve been slightly more successful in holding onto their share of the electorate:

Democrats’ advantage in leaned party affiliation appears to be expanding, as it was six points (46% to 40%) in the fourth quarter of 2017 compared with four points in both the second and third quarters. Gallup found similar Democratic gains late in the year in an analysis of monthly data from its daily tracking survey.

Nevertheless, they too will need to go after independent voters if they are to retake the House and/or Senate. Greater political independence “could also explain the more frequent changes in party control of Congress, with the majority party in the House of Representatives switching three times since 1994 — after the 1994, 2006 and 2010 midterm elections — after 40 consecutive years of Democratic House majorities,” Gallup finds. “Americans will vote in midterm elections this fall to elect a new Congress — and with an unpopular incumbent president, the increase in independents may only escalate the chances that party control of Congress will change hands once again.”

A word of caution is warranted. The presence of so many independent voters does not mean these are necessarily moderates. Most every poll shows the once-great center shrinking and more polarization at the extremes. If Democrats want to capitalize on the GOP woes and the general unpopularity of the president, they might want to consider running on his failure to carry through on populist economic reforms, his attacks on the health-care system, his self-deal and conflicts of interest and the Republicans utter failure to act as a restraint on the unhinged chief executive.