The latest poll by the non-partisan Kaiser Family Foundation found 46 percent of Americans support the healthcare bill and 42 percent oppose it.

The Democratic base appears to have rallied behind the legislation, which seeks to increase coverage to more than 30 million uninsured Americans. Three quarters of Democrats now support the bill, up from 70 percent last month. Republican opposition has hardened, going from 74 percent in February to 80 percent in the most recent poll, taken March 10.

Independents split over the measure, with 45 supporting it and 48 opposing.

Most surveys have found more Americans against the healthcare plan than for it, though the gap has been closing in recent weeks. The average of polls, taken before the release of the Kaiser survey Friday, found 49 percent against the bill and 43 percent for it.

Kaiser polls have generally found more support for the healthcare reform plan than other surveys. Kaiser's January poll found a 42-41, support-oppose split. The February poll had a 43-43 split.