WASHINGTON – Vice President Kamala Harris is expected to announce her running mate on Tuesday, as a new poll shows Pennsylvania Gov. Josh Shapiro and Arizona Sen. Mark Kelly enjoy higher approval ratings among Americans than Minnesota Gov. Tim Walz.

The NPR/PBS/Marist national poll, conducted between August 1 and 4, found that 31% of Americans have a favorable opinion of Kelly, while 18% have an unfavorable opinion. 25% of Americans have a favorable opinion of Shapiro, while 23% have an unfavorable opinion.

However, only 17 percent of Americans have a favorable opinion of Walz, while 12 percent have an unfavorable opinion. Seventy-one percent of Americans said they had never heard of Walz or were unsure how to rate him, compared to 52 percent for Kelly and 53 percent for Shapiro.

Reuters reported that the three men were on Harris’ shortlist for the vice presidential nomination until she narrowed her list to Walz and Shapiro.

The survey, conducted among 1,613 adults, has a margin of error of plus or minus 3.3 percentage points.

Harris and her new running mate will launch a multi-state blitz campaign on Tuesday, starting in Philadelphia.

This article originally appeared on USA TODAY: Poll: Josh Shapiro and Mark Kelly more popular than Tim Walz