Candidates can court the many public figures who pledged support to Booker ahead of the Iowa caucuses. The NJ senator had the most Iowa endorsements from officials and activists of any candidate in the race (Iowa Starting Line). While his endorsement list doesn't include Iowa's biggest names (Buttigieg and Biden secured endorsements from 2 of the 3 Iowa members of Congress, and Biden snagged former Iowa governor Vilsack), endorsements from activists and caucus-goers generate support for candidates in grassroots networks and make a better case for a candidate during the chaotic caucus process.
A Monmouth poll of Iowa caucusgoers released Monday, which was conducted before Booker dropped out, found that assigning Booker supporters to their second choices barely moved the needle. Biden, Buttigieg, Warren, and Klobuchar each went up a point. Sanders' support remained the same.