Amid growing calls for President Joe Biden to step aside due to concerns about his health and performance, the Biden campaign is testing Vice President Kamala Harris's electability against former President Donald Trump. A recent poll suggests Harris is gaining significant support among Democratic voters, with 73% approving of her as a potential replacement for Biden. Some prominent Democrats, including Jen Psaki, argue that Harris is the best alternative to Biden, but her unpopularity with certain voter segments remains a challenge. Meanwhile, Biden's aides are considering potential running mates for Harris, should she run, with Governors Roy Cooper, Andy Beshear, and Josh Shapiro being top contenders. Former President Trump has criticized Harris, calling her Biden's 'best insurance policy' due to her perceived unpopularity. Despite these developments, Biden has shown no intention of withdrawing from the race.