In an encouraging sign for the Democratic Party’s election prospects in 2018, its edge in party affiliation over the Republican Party has grown to seven percentage points, the largest it has been in over two years. During the late summer and fall of 2016, Democrats averaged a three-point advantage…

The growing Democratic advantage in recent months is mostly attributable to a decline in Republican affiliation rather than an increase in Democratic affiliation. Since November, the percentage of Republicans and Republican leaners has fallen four percentage points, while there has been a one-point rise in Democratic identification or leaning. The Republican decline has been offset mostly by a three-point increase in the percentage of Americans with no party preference or leaning.