text:  More of Biden's allies have raised concerns about his ability to beat Trump and serve another term in office, and some have been calling on Biden to step aside. Well, in a letter to Democratic lawmakers, Biden said he intends to stay in the presidential race. Earlier today, a defiant president called into the Morning Joe show on MSNBC. Here's NPR's Asma Khalid. Biden is digging in, dismissing calls from some prominent Democrats that he drop out. I don't care what those big names think.