Joe Biden, a two-term vice president, is now looking for his own understudy.

The presumptive 2020 Democratic presidential nominee had repeatedly said he wants a running mate who’s “simpatico” with him. But as he pivots from a relatively civil primary to the general election fight against President Trump, a combative and unpredictable candidate, he needs to decide whether he’d benefit from an equally pugnacious No. 2 who could lob political salvos Biden can’t or won’t.