Biden Spends Weekend Apologizing for Working With Segregationists

Joe Biden faced backlash for comments about working with segregationist senators, leading to apologies and a dip in his poll numbers. Kamala Harris and Elizabeth Warren have gained traction as a result. Despite the controversy, Biden remains a frontrunner, though his lead has narrowed.

Which two candidates have risen the most in the polls as mentioned in the text?

What does the text suggest about Biden's position in the polls compared to his rivals?